Tuesday, June 23, 2026

NEXUS: A UNIFIED PROGRAMMING LANGUAGE FOR ENTERPRISE AND EMBEDDED SYSTEMS DEVELOPMENT

 



                   


INTRODUCTION


The software development landscape has long been fragmented between languages optimized for enterprise systems and those designed for embedded environments. Enterprise developers typically work with languages that prioritize developer productivity, rich ecosystems, and scalability, while embedded systems programmers require fine-grained control over hardware resources, predictable performance, and minimal runtime overhead. This dichotomy forces organizations to maintain multiple codebases, split development teams, and duplicate effort when building systems that span both domains.


Nexus represents a paradigm shift in programming language design by unifying these traditionally separate worlds. It is a statically typed, compiled language that provides zero-cost abstractions, enabling developers to write high-level, expressive code that compiles down to efficient machine code suitable for resource-constrained embedded devices. Simultaneously, Nexus offers powerful features for building large-scale distributed systems, including sophisticated concurrency primitives, comprehensive standard libraries, and seamless integration with modern infrastructure.


The language achieves this duality through a carefully designed feature set that includes optional garbage collection, compile-time memory safety guarantees, flexible ownership semantics, and a powerful macro system. Developers can choose the level of control they need for each component of their system, using automatic memory management for business logic while maintaining manual control for performance-critical sections.


One of Nexus's most compelling features is its built-in support for heterogeneous computing across multiple GPU architectures. The language provides a unified abstraction layer that allows developers to write GPU-accelerated code once and deploy it across Intel, AMD ROCm, Apple Metal Performance Shaders, and Nvidia CUDA platforms. This capability is particularly valuable in the era of large language models and artificial intelligence, where computational workloads must efficiently utilize whatever hardware is available.



CORE LANGUAGE PHILOSOPHY AND DESIGN PRINCIPLES


Nexus is built on several foundational principles that guide its design and implementation. The first principle is progressive disclosure of complexity. Developers can start with simple, high-level constructs and progressively access lower-level features as their needs demand. A beginner can write productive code using automatic memory management and high-level abstractions, while an expert can drop down to manual memory control and inline assembly when necessary.


The second principle is zero-cost abstractions. High-level language features compile to machine code that is as efficient as hand-written low-level code. There is no runtime penalty for using abstractions like iterators, closures, or generic types. The compiler performs aggressive optimization and inlining to ensure that abstraction boundaries disappear in the final binary.


The third principle is explicit over implicit. While Nexus provides powerful type inference to reduce boilerplate, important decisions about resource management, error handling, and side effects are always visible in the code. This explicitness makes code easier to understand and maintain, particularly in large codebases with multiple contributors.


The fourth principle is composability and modularity. Nexus encourages building systems from small, well-defined components that can be composed in flexible ways. The module system supports both static and dynamic linking, allowing developers to choose the appropriate trade-offs for their deployment environment.



SYNTAX AND BASIC CONSTRUCTS


The syntax of Nexus draws inspiration from several language families while maintaining its own distinct character. It uses curly braces for block delimitation, semicolons as statement terminators, and a familiar function definition syntax. However, it introduces several innovations that make code more readable and maintainable.


Variable declarations use the keyword "let" for immutable bindings and "var" for mutable ones. Immutability is the default, encouraging functional programming patterns while still allowing mutation when necessary. Type annotations follow the variable name, separated by a colon, though type inference often makes them optional.


    let inference_batch_size: i32 = 32;

    var current_token_count = 0;  // Type inferred as i32

    

    let model_name = "llama-3-70b";  // Type inferred as string


Functions are defined using the "fn" keyword, with parameters and return types explicitly declared. The language supports both expression-based and statement-based function bodies. When a function body consists of a single expression, the return keyword can be omitted.


    fn calculate_attention_score(query: Vector, key: Vector) -> f32 {

        dot_product(query, key) / sqrt(query.dimension() as f32)

  }


The type system includes primitive types for integers of various sizes, floating-point numbers, booleans, and characters. Composite types include arrays, slices, tuples, structs, and enums. The language also supports generic types, allowing developers to write code that works with multiple concrete types while maintaining type safety.



TYPE SYSTEM AND MEMORY MANAGEMENT


Nexus employs a sophisticated type system that combines the safety of modern languages with the control required for systems programming. The type system is nominally typed for user-defined types and structurally typed for interfaces, providing flexibility in how components interact while maintaining strong compile-time guarantees.


The memory management model is one of Nexus's most innovative features. It supports three distinct modes that can be mixed within a single program. The first mode is automatic reference counting with cycle detection, suitable for most application code. The second mode is ownership-based manual management, similar to Rust, where the compiler tracks ownership and lifetimes to prevent memory errors. The third mode is explicit manual management using allocate and free operations, necessary for embedded systems and performance-critical code.


Developers can annotate types and functions to specify which memory management mode they use. The compiler enforces safety boundaries between modes, ensuring that unsafe manual memory management cannot corrupt the safety guarantees of automatic management.


    // Automatic memory management (default)

    struct LLMConfig {

        model_path: string,

        context_length: i32,

        temperature: f32,

        top_p: f32

    }

    

    // Manual ownership-based management

    struct @owned TokenBuffer {

        data: @owned [u8],

        capacity: usize,

        length: usize

    }

    

    // Explicit manual management for embedded systems

    struct @manual DeviceMemoryRegion {

        base_address: *mut u8,

        size: usize

    }


The ownership system tracks which part of the code is responsible for deallocating each resource. When a value goes out of scope, its destructor is automatically called, ensuring that resources are properly cleaned up. This pattern, known as Resource Acquisition Is Initialization, eliminates entire classes of bugs related to resource leaks.


For the LLM inference system we are building as our running example, we will use automatic memory management for configuration and high-level orchestration, while using ownership-based management for token buffers and model weights to ensure predictable performance.



CONCURRENCY AND PARALLELISM


Modern software systems must efficiently utilize multiple processor cores and handle concurrent operations. Nexus provides several concurrency primitives that work together to enable safe, efficient parallel execution.


The foundation of Nexus's concurrency model is the concept of isolated tasks. A task is a unit of concurrent execution that has its own stack and can communicate with other tasks through message passing or shared memory. The type system tracks which data can be safely shared between tasks, preventing data races at compile time.


    task fn process_token_batch(tokens: [Token], model: @shared LLMModel) -> [f32] {

        // This function runs as an independent task

        // The model is shared read-only across tasks

        // The tokens are moved into this task's ownership

        

        var embeddings: [f32] = [];

        for token in tokens {

            let embedding = model.get_embedding(token);

            embeddings.push(embedding);

        }

        return embeddings;

    }


Tasks can be spawned using the "spawn" keyword, which returns a handle that can be used to wait for the task's completion and retrieve its result. The runtime scheduler automatically distributes tasks across available processor cores, balancing load and minimizing context switching overhead.


For fine-grained parallelism, Nexus provides parallel iterators that automatically partition work across multiple threads. These iterators integrate seamlessly with the language's iterator protocol, allowing developers to parallelize existing sequential code with minimal changes.


    let token_embeddings = tokens

        .parallel_iter()

        .map(|token| model.get_embedding(token))

        .collect();


The language also supports async/await syntax for asynchronous I/O operations. Async functions return futures that represent values that will be available in the future. The runtime uses an efficient event loop to multiplex many concurrent async operations onto a small number of threads.


    async fn load_model_from_remote(url: string) -> Result<LLMModel, Error> {

        let response = await http_client.get(url);

        let model_data = await response.read_bytes();

        return LLMModel.deserialize(model_data);

    }



GPU ABSTRACTION AND HETEROGENEOUS COMPUTING


The ability to efficiently utilize GPU hardware is critical for modern applications, particularly those involving machine learning and large language models. However, the GPU landscape is highly fragmented, with different vendors providing incompatible programming models and APIs. Nexus addresses this challenge through a unified GPU abstraction layer that presents a consistent programming interface while generating optimized code for each target platform.


The abstraction is built on the concept of compute kernels, which are functions that execute in parallel across many GPU threads. Developers write kernels using a subset of the Nexus language that is compatible with GPU execution models. The compiler then translates these kernels to the appropriate backend, whether that is CUDA for Nvidia GPUs, ROCm for AMD GPUs, Metal for Apple devices, or SYCL for Intel GPUs.


    @gpu_kernel

    fn matrix_multiply_kernel(

        a: @gpu_buffer [f32],

        b: @gpu_buffer [f32],

        result: @gpu_buffer_mut [f32],

        m: i32,

        n: i32,

        k: i32

    ) {

        let row = gpu_thread_id().x;

        let col = gpu_thread_id().y;

        

        if row < m && col < n {

            var sum: f32 = 0.0;

            for i in 0..k {

                sum += a[row * k + i] * b[i * n + col];

            }

            result[row * n + col] = sum;

        }

    }


The GPU abstraction layer handles memory management, data transfer between host and device, and kernel launch configuration. Developers can explicitly control these aspects when necessary, but sensible defaults make it easy to get started.


    fn multiply_matrices_on_gpu(

        a: Matrix,

        b: Matrix,

        device: GpuDevice

    ) -> Matrix {

        // Allocate GPU memory and transfer data

        let a_gpu = device.allocate_buffer(a.data);

        let b_gpu = device.allocate_buffer(b.data);

        let result_gpu = device.allocate_buffer_uninit(a.rows * b.cols);

        

        // Configure kernel launch parameters

        let grid_dim = (a.rows / 16, b.cols / 16);

        let block_dim = (16, 16);

        

        // Launch kernel

        device.launch_kernel(

            matrix_multiply_kernel,

            grid_dim,

            block_dim,

            (a_gpu, b_gpu, result_gpu, a.rows, b.cols, a.cols)

        );

        

        // Transfer result back to host

        let result_data = device.read_buffer(result_gpu);

        return Matrix::new(a.rows, b.cols, result_data);

    }


The abstraction layer automatically detects available GPU devices at runtime and selects the most appropriate one based on developer-specified preferences. This allows the same binary to run efficiently on different hardware configurations without recompilation.


For our LLM inference system, GPU acceleration is essential for achieving acceptable performance. The matrix multiplications that dominate transformer model inference can be accelerated by orders of magnitude on GPU hardware compared to CPU execution.



LOCAL AND REMOTE LLM INTEGRATION


Large language models have become a fundamental building block for modern applications, but integrating them effectively requires careful consideration of deployment models, resource constraints, and latency requirements. Nexus provides first-class support for both local and remote LLM inference, allowing developers to choose the appropriate deployment strategy for their use case.


The language includes a comprehensive LLM integration library that abstracts over different model formats, inference engines, and deployment targets. Developers work with a unified API regardless of whether they are using a locally hosted model or calling a remote API service.


For local inference, the library supports loading models in various formats including GGUF, SafeTensors, and PyTorch checkpoints. The inference engine automatically selects the optimal execution strategy based on available hardware, utilizing GPU acceleration when available and falling back to optimized CPU implementations otherwise.


    struct LocalLLMEngine {

        model: TransformerModel,

        tokenizer: Tokenizer,

        device: ComputeDevice,

        config: InferenceConfig

    }

    

    impl LocalLLMEngine {

        fn new(model_path: string, device_preference: DevicePreference) -> Result<Self, Error> {

            // Detect available compute devices

            let available_devices = ComputeDevice.enumerate();

            let device = Self.select_device(available_devices, device_preference)?;

            

            // Load model and move to selected device

            let model = TransformerModel.load_from_file(model_path)?;

            model.to_device(device);

            

            // Load tokenizer from same directory

            let tokenizer = Tokenizer.load_from_directory(

                path.dirname(model_path)

            )?;

            

            let config = InferenceConfig.default();

            

            return Ok(Self { model, tokenizer, device, config });

        }

        

        fn generate(

            &self,

            prompt: string,

            max_tokens: i32,

            temperature: f32

        ) -> Result<string, Error> {

            // Tokenize input prompt

            let input_tokens = self.tokenizer.encode(prompt)?;

            

            // Prepare input tensor on device

            let input_tensor = Tensor.from_tokens(input_tokens, self.device);

            

            // Run inference loop

            var generated_tokens: [i32] = [];

            var current_input = input_tensor;

            

            for i in 0..max_tokens {

                // Forward pass through model

                let logits = self.model.forward(current_input);

                

                // Sample next token using temperature

                let next_token = self.sample_token(logits, temperature);

                

                // Check for end of sequence

                if next_token == self.tokenizer.eos_token_id {

                    break;

                }

                

                generated_tokens.push(next_token);

                

                // Prepare input for next iteration

                current_input = Tensor.from_single_token(next_token, self.device);

            }

            

            // Decode generated tokens to string

            let generated_text = self.tokenizer.decode(generated_tokens)?;

            return Ok(generated_text);

        }

        

        fn select_device(

            devices: [ComputeDevice],

            preference: DevicePreference

        ) -> Result<ComputeDevice, Error> {

            // Filter devices by preference

            let candidates = devices.filter(|d| {

                match preference {

                    DevicePreference.GpuOnly => d.is_gpu(),

                    DevicePreference.CpuOnly => d.is_cpu(),

                    DevicePreference.Any => true,

                    DevicePreference.Specific(arch) => d.architecture() == arch

                }

            });

            

            if candidates.is_empty() {

                return Err(Error.new("No suitable compute device found"));

            }

            

            // Select device with most memory

            let best_device = candidates.max_by_key(|d| d.available_memory());

            return Ok(best_device);

        }

        

        fn sample_token(&self, logits: Tensor, temperature: f32) -> i32 {

            // Apply temperature scaling

            let scaled_logits = logits / temperature;

            

            // Convert to probabilities using softmax

            let probs = softmax(scaled_logits);

            

            // Sample from probability distribution

            return sample_categorical(probs);

        }

    }


For remote inference, the library provides clients for popular API services while also supporting custom endpoints. The remote client handles authentication, request batching, retry logic, and error handling automatically.


    struct RemoteLLMEngine {

        endpoint: string,

        api_key: string,

        http_client: HttpClient,

        model_name: string

    }

    

    impl RemoteLLMEngine {

        fn new(endpoint: string, api_key: string, model_name: string) -> Self {

            let http_client = HttpClient.new()

                .with_timeout(Duration.seconds(30))

                .with_retry_policy(RetryPolicy.exponential_backoff(3));

            

            return Self { endpoint, api_key, http_client, model_name };

        }

        

        async fn generate(

            &self,

            prompt: string,

            max_tokens: i32,

            temperature: f32

        ) -> Result<string, Error> {

            // Construct API request

            let request_body = json!({

                "model": self.model_name,

                "prompt": prompt,

                "max_tokens": max_tokens,

                "temperature": temperature

            });

            

            // Send request to remote endpoint

            let response = await self.http_client

                .post(self.endpoint)

                .header("Authorization", "Bearer " + self.api_key)

                .json(request_body)

                .send()?;

            

            // Parse response

            if response.status_code() != 200 {

                return Err(Error.new("API request failed: " + response.status_text()));

            }

            

            let response_json = await response.json()?;

            let generated_text = response_json["choices"][0]["text"].as_string()?;

            

            return Ok(generated_text);

        }

    }


To provide a unified interface, both local and remote engines implement a common trait that defines the inference interface. This allows application code to be agnostic to the deployment model, making it easy to switch between local and remote inference or even use both simultaneously.


    trait LLMEngine {

        async fn generate(

            &self,

            prompt: string,

            max_tokens: i32,

            temperature: f32

        ) -> Result<string, Error>;

        

        fn supports_streaming(&self) -> bool;

        

        async fn generate_stream(

            &self,

            prompt: string,

            max_tokens: i32,

            temperature: f32

        ) -> Result<TokenStream, Error>;

    }


This abstraction enables sophisticated deployment strategies such as hybrid inference, where small requests are handled locally for low latency while large or complex requests are offloaded to remote services with more powerful hardware.



DEVICE ARCHITECTURE DETECTION AND OPTIMIZATION


One of the most challenging aspects of heterogeneous computing is efficiently utilizing diverse hardware architectures. Nexus addresses this through a comprehensive device detection and capability system that allows the runtime to make intelligent decisions about workload placement and optimization strategies.


The device enumeration system discovers all available compute devices at program startup, querying their capabilities, memory capacity, and performance characteristics. This information is used to build a device topology that represents the computational resources available to the application.


    struct ComputeDevice {

        id: DeviceId,

        name: string,

        architecture: DeviceArchitecture,

        memory_total: usize,

        memory_available: usize,

        compute_units: i32,

        max_work_group_size: i32,

        supports_fp64: bool,

        supports_fp16: bool

    }

    

    enum DeviceArchitecture {

        Cpu(CpuInfo),

        NvidiaCuda(CudaInfo),

        AmdRocm(RocmInfo),

        AppleMetal(MetalInfo),

        IntelSycl(SyclInfo)

    }

    

    impl ComputeDevice {

        fn enumerate() -> [ComputeDevice] {

            var devices: [ComputeDevice] = [];

            

            // Always include CPU as fallback

            devices.push(Self.enumerate_cpu());

            

            // Detect Nvidia CUDA devices

            if cuda_runtime_available() {

                devices.extend(Self.enumerate_cuda_devices());

            }

            

            // Detect AMD ROCm devices

            if rocm_runtime_available() {

                devices.extend(Self.enumerate_rocm_devices());

            }

            

            // Detect Apple Metal devices

            if metal_runtime_available() {

                devices.extend(Self.enumerate_metal_devices());

            }

            

            // Detect Intel SYCL devices

            if sycl_runtime_available() {

                devices.extend(Self.enumerate_sycl_devices());

            }

            

            return devices;

        }

        

        fn enumerate_cuda_devices() -> [ComputeDevice] {

            var devices: [ComputeDevice] = [];

            let device_count = cuda_get_device_count();

            

            for i in 0..device_count {

                let props = cuda_get_device_properties(i);

                

                let cuda_info = CudaInfo {

                    compute_capability: (props.major, props.minor),

                    multiprocessor_count: props.multiprocessor_count,

                    warp_size: props.warp_size

                };

                

                let device = ComputeDevice {

                    id: DeviceId.cuda(i),

                    name: props.name,

                    architecture: DeviceArchitecture.NvidiaCuda(cuda_info),

                    memory_total: props.total_global_mem,

                    memory_available: cuda_get_available_memory(i),

                    compute_units: props.multiprocessor_count,

                    max_work_group_size: props.max_threads_per_block,

                    supports_fp64: props.major >= 2,

                    supports_fp16: props.major >= 5

                };

                

                devices.push(device);

            }

            

            return devices;

        }

        

        fn is_gpu(&self) -> bool {

            match self.architecture {

                DeviceArchitecture.Cpu(_) => false,

                _ => true

            }

        }

        

        fn is_cpu(&self) -> bool {

            match self.architecture {

                DeviceArchitecture.Cpu(_) => true,

                _ => false

            }

        }

        

        fn available_memory(&self) -> usize {

            return self.memory_available;

        }

    }


The device selection logic considers multiple factors including available memory, compute capability, and workload characteristics. For LLM inference, memory capacity is often the primary constraint since large models can require tens of gigabytes of GPU memory.


When a model is too large to fit on a single device, Nexus supports automatic model parallelism, splitting the model across multiple devices and coordinating data transfer between them. This is handled transparently by the runtime, though developers can provide hints to optimize the partitioning strategy.



TRANSFORMER MODEL IMPLEMENTATION


The core of any LLM system is the transformer architecture, which consists of stacked layers of self-attention and feed-forward networks. Implementing this efficiently requires careful attention to memory layout, numerical precision, and computational optimization. Nexus provides high-level abstractions for building neural network models while still allowing fine-grained control over performance-critical operations.


The transformer model is composed of several key components. The embedding layer converts discrete tokens into continuous vector representations. The attention mechanism allows the model to weigh the importance of different input positions when processing each token. The feed-forward network applies non-linear transformations to the attention outputs. Layer normalization stabilizes training and improves convergence.


    struct TransformerModel {

        config: ModelConfig,

        token_embeddings: EmbeddingLayer,

        position_embeddings: EmbeddingLayer,

        layers: [TransformerLayer],

        output_norm: LayerNorm,

        output_projection: LinearLayer,

        device: ComputeDevice

    }

    

    struct TransformerLayer {

        attention: MultiHeadAttention,

        attention_norm: LayerNorm,

        feed_forward: FeedForwardNetwork,

        ffn_norm: LayerNorm

    }

    

    struct MultiHeadAttention {

        num_heads: i32,

        head_dim: i32,

        query_proj: LinearLayer,

        key_proj: LinearLayer,

        value_proj: LinearLayer,

        output_proj: LinearLayer,

        kv_cache: Option<KVCache>

    }

    

    struct FeedForwardNetwork {

        gate_proj: LinearLayer,

        up_proj: LinearLayer,

        down_proj: LinearLayer,

        activation: ActivationFunction

    }


The forward pass through the model processes input tokens through each layer sequentially, accumulating the transformations to produce output logits that represent the probability distribution over the vocabulary for the next token.


    impl TransformerModel {

        fn forward(&self, input_tokens: Tensor) -> Tensor {

            // Get token embeddings

            var hidden_states = self.token_embeddings.forward(input_tokens);

            

            // Add position embeddings

            let positions = Tensor.arange(0, input_tokens.size(0), self.device);

            let position_embeds = self.position_embeddings.forward(positions);

            hidden_states = hidden_states + position_embeds;

            

            // Process through transformer layers

            for layer in self.layers {

                hidden_states = layer.forward(hidden_states);

            }

            

            // Apply output normalization

            hidden_states = self.output_norm.forward(hidden_states);

            

            // Project to vocabulary size

            let logits = self.output_projection.forward(hidden_states);

            

            return logits;

        }

        

        fn load_from_file(path: string) -> Result<Self, Error> {

            // Open model file

            let file = File.open(path)?;

            let reader = SafeTensorsReader.new(file)?;

            

            // Read model configuration

            let config_json = reader.read_metadata("config")?;

            let config = ModelConfig.from_json(config_json)?;

            

            // Initialize model structure

            var model = Self.new_uninitialized(config);

            

            // Load weights for each component

            model.token_embeddings.load_weights(&reader, "token_embeddings")?;

            model.position_embeddings.load_weights(&reader, "position_embeddings")?;

            

            for i in 0..model.layers.len() {

                let prefix = "layers." + i.to_string();

                model.layers[i].load_weights(&reader, prefix)?;

            }

            

            model.output_norm.load_weights(&reader, "output_norm")?;

            model.output_projection.load_weights(&reader, "output_projection")?;

            

            return Ok(model);

        }

        

        fn to_device(&mut self, device: ComputeDevice) {

            self.device = device;

            

            // Move all parameters to target device

            self.token_embeddings.to_device(device);

            self.position_embeddings.to_device(device);

            

            for layer in &mut self.layers {

                layer.to_device(device);

            }

            

            self.output_norm.to_device(device);

            self.output_projection.to_device(device);

        }

    }


The transformer layer implements the residual connections and layer normalization that are characteristic of the architecture. Each sub-component processes the input and its output is added back to the original input before being normalized.


    impl TransformerLayer {

        fn forward(&self, input: Tensor) -> Tensor {

            // Self-attention with residual connection

            var hidden = self.attention_norm.forward(input);

            hidden = self.attention.forward(hidden);

            hidden = input + hidden;

            

            // Feed-forward network with residual connection

            var ffn_input = self.ffn_norm.forward(hidden);

            ffn_input = self.feed_forward.forward(ffn_input);

            hidden = hidden + ffn_input;

            

            return hidden;

        }

        

        fn load_weights(&mut self, reader: &SafeTensorsReader, prefix: string) -> Result<(), Error> {

            self.attention.load_weights(reader, prefix + ".attention")?;

            self.attention_norm.load_weights(reader, prefix + ".attention_norm")?;

            self.feed_forward.load_weights(reader, prefix + ".feed_forward")?;

            self.ffn_norm.load_weights(reader, prefix + ".ffn_norm")?;

            return Ok(());

        }

        

        fn to_device(&mut self, device: ComputeDevice) {

            self.attention.to_device(device);

            self.attention_norm.to_device(device);

            self.feed_forward.to_device(device);

            self.ffn_norm.to_device(device);

        }

    }


The multi-head attention mechanism is the most computationally intensive part of the transformer. It computes attention scores between all pairs of input positions, allowing the model to capture long-range dependencies. The computation is parallelized across multiple attention heads, each of which learns to focus on different aspects of the input.


    impl MultiHeadAttention {

        fn forward(&self, input: Tensor) -> Tensor {

            let batch_size = input.size(0);

            let seq_len = input.size(1);

            let hidden_dim = input.size(2);

            

            // Project input to query, key, and value

            let queries = self.query_proj.forward(input);

            let keys = self.key_proj.forward(input);

            let values = self.value_proj.forward(input);

            

            // Reshape to separate heads

            let queries = queries.reshape(

                batch_size,

                seq_len,

                self.num_heads,

                self.head_dim

            ).transpose(1, 2);

            

            let keys = keys.reshape(

                batch_size,

                seq_len,

                self.num_heads,

                self.head_dim

            ).transpose(1, 2);

            

            let values = values.reshape(

                batch_size,

                seq_len,

                self.num_heads,

                self.head_dim

            ).transpose(1, 2);

            

            // Compute attention scores

            let scale = 1.0 / sqrt(self.head_dim as f32);

            var attention_scores = queries.matmul(keys.transpose(-2, -1)) * scale;

            

            // Apply causal mask to prevent attending to future positions

            let causal_mask = self.create_causal_mask(seq_len);

            attention_scores = attention_scores + causal_mask;

            

            // Convert scores to probabilities

            let attention_probs = softmax(attention_scores, dim: -1);

            

            // Apply attention to values

            var output = attention_probs.matmul(values);

            

            // Reshape back to original dimensions

            output = output.transpose(1, 2).reshape(

                batch_size,

                seq_len,

                self.num_heads * self.head_dim

            );

            

            // Final output projection

            output = self.output_proj.forward(output);

            

            return output;

        }

        

        fn create_causal_mask(&self, seq_len: i32) -> Tensor {

            // Create upper triangular matrix of negative infinity

            var mask = Tensor.full((seq_len, seq_len), f32.neg_infinity());

            

            for i in 0..seq_len {

                for j in 0..=i {

                    mask[i, j] = 0.0;

                }

            }

            

            return mask;

        }

        

        fn load_weights(&mut self, reader: &SafeTensorsReader, prefix: string) -> Result<(), Error> {

            self.query_proj.load_weights(reader, prefix + ".query_proj")?;

            self.key_proj.load_weights(reader, prefix + ".key_proj")?;

            self.value_proj.load_weights(reader, prefix + ".value_proj")?;

            self.output_proj.load_weights(reader, prefix + ".output_proj")?;

            return Ok(());

        }

        

        fn to_device(&mut self, device: ComputeDevice) {

            self.query_proj.to_device(device);

            self.key_proj.to_device(device);

            self.value_proj.to_device(device);

            self.output_proj.to_device(device);

        }

    }



TENSOR OPERATIONS AND GPU ACCELERATION


The tensor abstraction is fundamental to implementing neural networks efficiently. A tensor is a multi-dimensional array with associated metadata about its shape, data type, and storage device. Nexus provides a comprehensive tensor library that supports both CPU and GPU execution, with operations automatically dispatched to the appropriate backend based on where the tensor data resides.


    struct Tensor {

        data: TensorStorage,

        shape: [i32],

        stride: [i32],

        dtype: DataType,

        device: ComputeDevice

    }

    

    enum TensorStorage {

        Cpu(@owned [u8]),

        Gpu(GpuBuffer)

    }

    

    enum DataType {

        Float32,

        Float16,

        Int32,

        Int64,

        UInt8

    }

    

    impl Tensor {

        fn new(shape: [i32], dtype: DataType, device: ComputeDevice) -> Self {

            let num_elements = shape.product();

            let element_size = dtype.size_bytes();

            let total_bytes = num_elements * element_size;

            

            let storage = match device.is_gpu() {

                true => TensorStorage.Gpu(device.allocate_buffer(total_bytes)),

                false => TensorStorage.Cpu(allocate_aligned(total_bytes, 64))

            };

            

            let stride = Self.compute_stride(shape);

            

            return Self { data: storage, shape, stride, dtype, device };

        }

        

        fn from_slice(data: [f32], shape: [i32], device: ComputeDevice) -> Self {

            var tensor = Self.new(shape, DataType.Float32, device);

            

            match tensor.data {

                TensorStorage.Cpu(buffer) => {

                    // Copy data directly to CPU buffer

                    memory_copy(buffer.as_ptr(), data.as_ptr(), data.len() * 4);

                },

                TensorStorage.Gpu(buffer) => {

                    // Upload data to GPU

                    device.write_buffer(buffer, data.as_bytes());

                }

            }

            

            return tensor;

        }

        

        fn matmul(&self, other: &Tensor) -> Tensor {

            // Validate dimensions for matrix multiplication

            assert(self.shape.len() >= 2, "First tensor must be at least 2D");

            assert(other.shape.len() >= 2, "Second tensor must be at least 2D");

            

            let m = self.shape[self.shape.len() - 2];

            let k = self.shape[self.shape.len() - 1];

            let k2 = other.shape[other.shape.len() - 2];

            let n = other.shape[other.shape.len() - 1];

            

            assert(k == k2, "Inner dimensions must match");

            

            // Compute output shape

            var output_shape = self.shape.clone();

            output_shape[output_shape.len() - 2] = m;

            output_shape[output_shape.len() - 1] = n;

            

            // Create output tensor on same device

            var result = Tensor.new(output_shape, self.dtype, self.device);

            

            // Dispatch to appropriate backend

            if self.device.is_gpu() {

                self.matmul_gpu(other, &mut result);

            } else {

                self.matmul_cpu(other, &mut result);

            }

            

            return result;

        }

        

        fn matmul_gpu(&self, other: &Tensor, result: &mut Tensor) {

            // Extract matrix dimensions

            let m = self.shape[self.shape.len() - 2];

            let k = self.shape[self.shape.len() - 1];

            let n = other.shape[other.shape.len() - 1];

            

            // Get GPU buffers

            let a_buffer = self.data.as_gpu_buffer();

            let b_buffer = other.data.as_gpu_buffer();

            let c_buffer = result.data.as_gpu_buffer_mut();

            

            // Configure kernel launch

            let block_size = 16;

            let grid_x = (m + block_size - 1) / block_size;

            let grid_y = (n + block_size - 1) / block_size;

            

            // Launch matrix multiplication kernel

            self.device.launch_kernel(

                matrix_multiply_kernel,

                (grid_x, grid_y, 1),

                (block_size, block_size, 1),

                (a_buffer, b_buffer, c_buffer, m, n, k)

            );

        }

        

        fn matmul_cpu(&self, other: &Tensor, result: &mut Tensor) {

            // Extract matrix dimensions

            let m = self.shape[self.shape.len() - 2];

            let k = self.shape[self.shape.len() - 1];

            let n = other.shape[other.shape.len() - 1];

            

            // Get raw data pointers

            let a_data = self.data.as_cpu_slice_f32();

            let b_data = other.data.as_cpu_slice_f32();

            let c_data = result.data.as_cpu_slice_mut_f32();

            

            // Use optimized BLAS implementation

            cblas_sgemm(

                CblasRowMajor,

                CblasNoTrans,

                CblasNoTrans,

                m, n, k,

                1.0,

                a_data.as_ptr(), k,

                b_data.as_ptr(), n,

                0.0,

                c_data.as_mut_ptr(), n

            );

        }

        

        fn to_device(&self, target_device: ComputeDevice) -> Tensor {

            if self.device.id == target_device.id {

                return self.clone();

            }

            

            // Create new tensor on target device

            var result = Tensor.new(self.shape.clone(), self.dtype, target_device);

            

            // Copy data between devices

            match (self.data, result.data) {

                (TensorStorage.Cpu(src), TensorStorage.Cpu(dst)) => {

                    memory_copy(dst.as_mut_ptr(), src.as_ptr(), src.len());

                },

                (TensorStorage.Cpu(src), TensorStorage.Gpu(dst)) => {

                    target_device.write_buffer(dst, src);

                },

                (TensorStorage.Gpu(src), TensorStorage.Cpu(dst)) => {

                    self.device.read_buffer(src, dst);

                },

                (TensorStorage.Gpu(src), TensorStorage.Gpu(dst)) => {

                    // Peer-to-peer GPU transfer if supported

                    if self.device.supports_p2p(target_device) {

                        self.device.copy_buffer_p2p(src, dst, target_device);

                    } else {

                        // Transfer through CPU as intermediate

                        let temp = allocate_aligned(src.size(), 64);

                        self.device.read_buffer(src, temp);

                        target_device.write_buffer(dst, temp);

                        deallocate(temp);

                    }

                }

            }

            

            return result;

        }

        

        fn compute_stride(shape: [i32]) -> [i32] {

            var stride: [i32] = [];

            var current_stride = 1;

            

            for i in (0..shape.len()).rev() {

                stride.insert(0, current_stride);

                current_stride *= shape[i];

            }

            

            return stride;

        }

    }



TOKENIZATION AND TEXT PROCESSING


Before text can be processed by a language model, it must be converted into a sequence of discrete tokens. Tokenization is the process of splitting text into these tokens, which typically represent subword units that balance vocabulary size with the ability to represent arbitrary text. Nexus provides a flexible tokenization framework that supports multiple tokenization algorithms including Byte Pair Encoding, WordPiece, and SentencePiece.


    struct Tokenizer {

        vocab: Vocabulary,

        merges: [TokenMerge],

        special_tokens: SpecialTokens,

        encoding_type: EncodingType

    }

    

    struct Vocabulary {

        token_to_id: HashMap<string, i32>,

        id_to_token: HashMap<i32, string>,

        size: i32

    }

    

    struct SpecialTokens {

        bos_token_id: i32,

        eos_token_id: i32,

        pad_token_id: i32,

        unk_token_id: i32

    }

    

    enum EncodingType {

        BytePairEncoding,

        WordPiece,

        SentencePiece

    }

    

    impl Tokenizer {

        fn load_from_directory(path: string) -> Result<Self, Error> {

            // Load vocabulary file

            let vocab_path = path + "/vocab.json";

            let vocab_json = File.read_to_string(vocab_path)?;

            let vocab = Vocabulary.from_json(vocab_json)?;

            

            // Load merges file for BPE

            let merges_path = path + "/merges.txt";

            let merges = if File.exists(merges_path) {

                Self.load_merges(merges_path)?

            } else {

                []

            };

            

            // Load special tokens configuration

            let special_tokens_path = path + "/special_tokens.json";

            let special_tokens_json = File.read_to_string(special_tokens_path)?;

            let special_tokens = SpecialTokens.from_json(special_tokens_json)?;

            

            // Determine encoding type from configuration

            let config_path = path + "/tokenizer_config.json";

            let config_json = File.read_to_string(config_path)?;

            let encoding_type = Self.parse_encoding_type(config_json)?;

            

            return Ok(Self { vocab, merges, special_tokens, encoding_type });

        }

        

        fn encode(&self, text: string) -> Result<[i32], Error> {

            // Normalize text

            let normalized = self.normalize_text(text);

            

            // Pre-tokenize into words

            let words = self.pre_tokenize(normalized);

            

            // Apply subword tokenization

            var token_ids: [i32] = [];

            

            for word in words {

                let subword_tokens = match self.encoding_type {

                    EncodingType.BytePairEncoding => self.encode_bpe(word),

                    EncodingType.WordPiece => self.encode_wordpiece(word),

                    EncodingType.SentencePiece => self.encode_sentencepiece(word)

                };

                

                token_ids.extend(subword_tokens);

            }

            

            return Ok(token_ids);

        }

        

        fn decode(&self, token_ids: [i32]) -> Result<string, Error> {

            var tokens: [string] = [];

            

            for id in token_ids {

                // Skip special tokens

                if id == self.special_tokens.pad_token_id {

                    continue;

                }

                

                // Look up token in vocabulary

                let token = self.vocab.id_to_token.get(id)

                    .ok_or(Error.new("Unknown token id: " + id.to_string()))?;

                

                tokens.push(token);

            }

            

            // Join tokens and clean up

            let text = tokens.join("");

            let cleaned = self.post_process_decoded_text(text);

            

            return Ok(cleaned);

        }

        

        fn encode_bpe(&self, word: string) -> [i32] {

            // Start with character-level tokens

            var current_tokens: [string] = word.chars()

                .map(|c| c.to_string())

                .collect();

            

            // Apply merges iteratively

            loop {

                // Find the highest priority merge that can be applied

                var best_merge: Option<(usize, TokenMerge)> = None;

                var best_priority = i32.max_value();

                

                for i in 0..(current_tokens.len() - 1) {

                    let pair = (current_tokens[i], current_tokens[i + 1]);

                    

                    for (priority, merge) in self.merges.enumerate() {

                        if merge.matches(pair) && priority < best_priority {

                            best_merge = Some((i, merge));

                            best_priority = priority;

                        }

                    }

                }

                

                // If no merge found, we're done

                if best_merge.is_none() {

                    break;

                }

                

                // Apply the best merge

                let (pos, merge) = best_merge.unwrap();

                let merged = merge.result;

                current_tokens[pos] = merged;

                current_tokens.remove(pos + 1);

            }

            

            // Convert tokens to IDs

            var token_ids: [i32] = [];

            for token in current_tokens {

                let id = self.vocab.token_to_id.get(token)

                    .unwrap_or(self.special_tokens.unk_token_id);

                token_ids.push(id);

            }

            

            return token_ids;

        }

        

        fn normalize_text(&self, text: string) -> string {

            // Convert to lowercase

            var normalized = text.to_lowercase();

            

            // Remove extra whitespace

            normalized = normalized.trim();

            normalized = normalized.replace_all("  ", " ");

            

            return normalized;

        }

        

        fn pre_tokenize(&self, text: string) -> [string] {

            // Split on whitespace and punctuation

            var words: [string] = [];

            var current_word = "";

            

            for ch in text.chars() {

                if ch.is_whitespace() || ch.is_punctuation() {

                    if !current_word.is_empty() {

                        words.push(current_word);

                        current_word = "";

                    }

                    if ch.is_punctuation() {

                        words.push(ch.to_string());

                    }

                } else {

                    current_word.push(ch);

                }

            }

            

            if !current_word.is_empty() {

                words.push(current_word);

            }

            

            return words;

        }

        

        fn post_process_decoded_text(&self, text: string) -> string {

            // Replace special byte-level tokens

            var processed = text.replace_all("Ä ", " ");

            processed = processed.replace_all("ÄŠ", "\n");

            

            // Clean up spacing

            processed = processed.trim();

            

            return processed;

        }

    }



ENTERPRISE FEATURES AND SCALABILITY


For enterprise deployments, Nexus provides comprehensive features for building reliable, scalable systems. These include sophisticated error handling, structured logging, metrics collection, distributed tracing, and configuration management. The language's standard library includes production-ready implementations of these features that integrate seamlessly with popular observability platforms.


Error handling in Nexus uses a Result type that forces developers to explicitly handle error cases. This eliminates the entire class of bugs caused by unchecked exceptions while maintaining ergonomic error propagation through the question mark operator.


    enum Result<T, E> {

        Ok(T),

        Err(E)

    }

    

    impl<T, E> Result<T, E> {

        fn unwrap(self) -> T {

            match self {

                Result.Ok(value) => value,

                Result.Err(error) => panic("Called unwrap on Err value")

            }

        }

        

        fn unwrap_or(self, default: T) -> T {

            match self {

                Result.Ok(value) => value,

                Result.Err(_) => default

            }

        }

        

        fn map<U>(self, f: fn(T) -> U) -> Result<U, E> {

            match self {

                Result.Ok(value) => Result.Ok(f(value)),

                Result.Err(error) => Result.Err(error)

            }

        }

    }


The logging system provides structured logging with multiple severity levels and automatic context propagation. Log messages can include arbitrary structured data that is preserved through the logging pipeline, making it easy to search and analyze logs in production systems.


    struct Logger {

        name: string,

        level: LogLevel,

        handlers: [LogHandler]

    }

    

    enum LogLevel {

        Debug,

        Info,

        Warning,

        Error,

        Critical

    }

    

    impl Logger {

        fn new(name: string) -> Self {

            let level = LogLevel.Info;

            let handlers = [LogHandler.console()];

            return Self { name, level, handlers };

        }

        

        fn info(&self, message: string, context: HashMap<string, Value>) {

            if self.level <= LogLevel.Info {

                let record = LogRecord {

                    timestamp: SystemTime.now(),

                    level: LogLevel.Info,

                    logger_name: self.name,

                    message: message,

                    context: context

                };

                

                for handler in self.handlers {

                    handler.emit(record);

                }

            }

        }

        

        fn error(&self, message: string, error: Error, context: HashMap<string, Value>) {

            if self.level <= LogLevel.Error {

                var full_context = context.clone();

                full_context.insert("error", error.to_value());

                full_context.insert("error_trace", error.backtrace().to_value());

                

                let record = LogRecord {

                    timestamp: SystemTime.now(),

                    level: LogLevel.Error,

                    logger_name: self.name,

                    message: message,

                    context: full_context

                };

                

                for handler in self.handlers {

                    handler.emit(record);

                }

            }

        }

    }


For distributed systems, Nexus provides built-in support for service discovery, load balancing, and circuit breaking. These patterns are essential for building resilient microservices that can tolerate partial failures and network issues.



EMBEDDED SYSTEMS SUPPORT


While Nexus excels at building large-scale enterprise systems, it is equally capable of targeting resource-constrained embedded devices. The language provides fine-grained control over memory allocation, supports bare-metal programming without an operating system, and can generate extremely compact binaries.


For embedded targets, developers can disable the standard library and runtime, using only the core language features and a minimal runtime that provides basic memory management and panic handling. This allows Nexus programs to run on microcontrollers with just a few kilobytes of RAM.


    #![no_std]

    #![no_runtime]

    

    // Entry point for embedded system

    @entry

    fn main() -> ! {

        // Initialize hardware

        let mut gpio = Gpio.init();

        let mut timer = Timer.init();

        

        // Configure LED pin as output

        gpio.set_mode(Pin.D13, PinMode.Output);

        

        // Main loop

        loop {

            gpio.write(Pin.D13, true);

            timer.delay_ms(1000);

            

            gpio.write(Pin.D13, false);

            timer.delay_ms(1000);

        }

    }


The language supports direct memory-mapped I/O for accessing hardware registers, inline assembly for performance-critical code, and interrupt handlers for responding to hardware events. These features make it possible to write device drivers and real-time control systems entirely in Nexus.


For embedded LLM inference, Nexus can target edge devices with neural processing units or other specialized accelerators. The same high-level model code can be compiled for both server-class GPUs and embedded NPUs, with the compiler automatically adapting to the capabilities of the target hardware.



PRODUCTION-READY RUNNING EXAMPLE: UNIFIED LLM INFERENCE SYSTEM


The following is a complete, production-ready implementation of a unified LLM inference system that supports both local and remote models, multiple GPU architectures, and can be deployed in both enterprise and embedded environments. This system demonstrates all the key features of Nexus discussed throughout this article.


    // Main module for unified LLM inference system

    module llm_inference;

    

    use std.io.{File, Error};

    use std.collections.HashMap;

    use std.sync.{Mutex, Arc};

    use std.async.{Future, Runtime};

    use std.net.HttpClient;

    use std.gpu.{ComputeDevice, GpuBuffer, DeviceArchitecture};

    use std.ml.{Tensor, TensorStorage, DataType};

    use std.logging.{Logger, LogLevel};

    

    // Configuration for the inference system

    struct InferenceSystemConfig {

        local_model_path: Option<string>,

        remote_endpoint: Option<string>,

        remote_api_key: Option<string>,

        device_preference: DevicePreference,

        max_batch_size: i32,

        max_context_length: i32,

        enable_kv_cache: bool,

        log_level: LogLevel

    }

    

    enum DevicePreference {

        GpuOnly,

        CpuOnly,

        Any,

        Specific(DeviceArchitecture)

    }

    

    // Main inference system that coordinates local and remote engines

    struct InferenceSystem {

        config: InferenceSystemConfig,

        local_engine: Option<LocalLLMEngine>,

        remote_engine: Option<RemoteLLMEngine>,

        device: ComputeDevice,

        logger: Logger,

        metrics: Arc<Mutex<SystemMetrics>>

    }

    

    struct SystemMetrics {

        total_requests: i64,

        total_tokens_generated: i64,

        average_latency_ms: f64,

        gpu_memory_used_bytes: usize,

        cache_hit_rate: f64

    }

    

    impl InferenceSystem {

        fn new(config: InferenceSystemConfig) -> Result<Self, Error> {

            // Initialize logger

            let logger = Logger.new("llm_inference");

            logger.set_level(config.log_level);

            

            logger.info("Initializing inference system", hashmap!{

                "device_preference" => config.device_preference.to_string()

            });

            

            // Detect and select compute device

            let available_devices = ComputeDevice.enumerate();

            logger.info("Detected compute devices", hashmap!{

                "count" => available_devices.len().to_string()

            });

            

            for device in &available_devices {

                logger.info("Available device", hashmap!{

                    "name" => device.name.clone(),

                    "architecture" => device.architecture.to_string(),

                    "memory_gb" => (device.memory_total / (1024 * 1024 * 1024)).to_string()

                });

            }

            

            let device = Self.select_best_device(

                available_devices,

                config.device_preference

            )?;

            

            logger.info("Selected compute device", hashmap!{

                "name" => device.name.clone(),

                "architecture" => device.architecture.to_string()

            });

            

            // Initialize local engine if model path provided

            let local_engine = if let Some(model_path) = &config.local_model_path {

                logger.info("Loading local model", hashmap!{

                    "path" => model_path.clone()

                });

                

                let engine = LocalLLMEngine.new(

                    model_path.clone(),

                    device,

                    config.max_batch_size,

                    config.enable_kv_cache

                )?;

                

                logger.info("Local model loaded successfully", hashmap!{

                    "parameters" => engine.model.parameter_count().to_string()

                });

                

                Some(engine)

            } else {

                None

            };

            

            // Initialize remote engine if endpoint provided

            let remote_engine = if let Some(endpoint) = &config.remote_endpoint {

                logger.info("Initializing remote engine", hashmap!{

                    "endpoint" => endpoint.clone()

                });

                

                let api_key = config.remote_api_key.clone()

                    .ok_or(Error.new("Remote API key required"))?;

                

                Some(RemoteLLMEngine.new(

                    endpoint.clone(),

                    api_key,

                    "default".to_string()

                ))

            } else {

                None

            };

            

            // Validate that at least one engine is available

            if local_engine.is_none() && remote_engine.is_none() {

                return Err(Error.new(

                    "At least one of local_model_path or remote_endpoint must be provided"

                ));

            }

            

            let metrics = Arc.new(Mutex.new(SystemMetrics {

                total_requests: 0,

                total_tokens_generated: 0,

                average_latency_ms: 0.0,

                gpu_memory_used_bytes: 0,

                cache_hit_rate: 0.0

            }));

            

            logger.info("Inference system initialized successfully", hashmap!{});

            

            return Ok(Self {

                config,

                local_engine,

                remote_engine,

                device,

                logger,

                metrics

            });

        }

        

        async fn generate(

            &self,

            prompt: string,

            max_tokens: i32,

            temperature: f32,

            top_p: f32,

            use_local: bool

        ) -> Result<GenerationResult, Error> {

            let start_time = SystemTime.now();

            

            self.logger.info("Starting generation", hashmap!{

                "prompt_length" => prompt.len().to_string(),

                "max_tokens" => max_tokens.to_string(),

                "use_local" => use_local.to_string()

            });

            

            // Update metrics

            {

                let mut metrics = self.metrics.lock();

                metrics.total_requests += 1;

            }

            

            // Choose engine based on preference and availability

            let result = if use_local && self.local_engine.is_some() {

                let engine = self.local_engine.as_ref().unwrap();

                self.generate_local(engine, prompt, max_tokens, temperature, top_p).await?

            } else if self.remote_engine.is_some() {

                let engine = self.remote_engine.as_ref().unwrap();

                self.generate_remote(engine, prompt, max_tokens, temperature).await?

            } else {

                return Err(Error.new("No suitable engine available"));

            };

            

            let elapsed_ms = SystemTime.now().duration_since(start_time).as_millis();

            

            // Update metrics

            {

                let mut metrics = self.metrics.lock();

                metrics.total_tokens_generated += result.tokens_generated as i64;

                

                let total_requests = metrics.total_requests as f64;

                metrics.average_latency_ms = 

                    (metrics.average_latency_ms * (total_requests - 1.0) + elapsed_ms as f64) 

                    / total_requests;

            }

            

            self.logger.info("Generation completed", hashmap!{

                "tokens_generated" => result.tokens_generated.to_string(),

                "elapsed_ms" => elapsed_ms.to_string(),

                "tokens_per_second" => (result.tokens_generated as f64 / (elapsed_ms as f64 / 1000.0)).to_string()

            });

            

            return Ok(result);

        }

        

        async fn generate_local(

            &self,

            engine: &LocalLLMEngine,

            prompt: string,

            max_tokens: i32,

            temperature: f32,

            top_p: f32

        ) -> Result<GenerationResult, Error> {

            // Tokenize input

            let input_tokens = engine.tokenizer.encode(prompt)?;

            

            self.logger.debug("Tokenized input", hashmap!{

                "token_count" => input_tokens.len().to_string()

            });

            

            // Validate context length

            if input_tokens.len() + max_tokens > self.config.max_context_length {

                return Err(Error.new("Input too long for context window"));

            }

            

            // Create input tensor on device

            let input_tensor = Tensor.from_slice(

                input_tokens.map(|t| t as f32),

                [1, input_tokens.len() as i32],

                self.device

            );

            

            // Run generation loop

            var generated_tokens: [i32] = [];

            var current_input = input_tensor;

            var total_logprob = 0.0;

            

            for step in 0..max_tokens {

                // Forward pass through model

                let logits = engine.model.forward(current_input);

                

                // Extract logits for last position

                let last_logits = logits.slice([-1, ..]);

                

                // Apply temperature and top-p sampling

                let next_token_result = self.sample_token(

                    last_logits,

                    temperature,

                    top_p

                );

                

                let next_token = next_token_result.token_id;

                total_logprob += next_token_result.log_probability;

                

                // Check for end of sequence

                if next_token == engine.tokenizer.special_tokens.eos_token_id {

                    self.logger.debug("EOS token generated", hashmap!{

                        "step" => step.to_string()

                    });

                    break;

                }

                

                generated_tokens.push(next_token);

                

                // Prepare input for next iteration

                current_input = Tensor.from_slice(

                    [next_token as f32],

                    [1, 1],

                    self.device

                );

                

                // Log progress periodically

                if step % 10 == 0 {

                    self.logger.debug("Generation progress", hashmap!{

                        "step" => step.to_string(),

                        "tokens_generated" => generated_tokens.len().to_string()

                    });

                }

            }

            

            // Decode generated tokens

            let generated_text = engine.tokenizer.decode(generated_tokens)?;

            

            return Ok(GenerationResult {

                text: generated_text,

                tokens_generated: generated_tokens.len() as i32,

                average_log_probability: total_logprob / generated_tokens.len() as f64,

                finish_reason: if generated_tokens.len() == max_tokens {

                    FinishReason.MaxTokens

                } else {

                    FinishReason.EndOfSequence

                }

            });

        }

        

        async fn generate_remote(

            &self,

            engine: &RemoteLLMEngine,

            prompt: string,

            max_tokens: i32,

            temperature: f32

        ) -> Result<GenerationResult, Error> {

            let result = await engine.generate(prompt, max_tokens, temperature)?;

            return Ok(result);

        }

        

        fn sample_token(

            &self,

            logits: Tensor,

            temperature: f32,

            top_p: f32

        ) -> SamplingResult {

            // Move logits to CPU for sampling

            let logits_cpu = logits.to_cpu();

            let log


Continuing from where I stopped:


        fn sample_token(

            &self,

            logits: Tensor,

            temperature: f32,

            top_p: f32

        ) -> SamplingResult {

            // Move logits to CPU for sampling

            let logits_cpu = logits.to_cpu();

            let logits_data = logits_cpu.as_slice_f32();

            

            // Apply temperature scaling

            var scaled_logits: [f32] = [];

            for logit in logits_data {

                scaled_logits.push(logit / temperature);

            }

            

            // Convert to probabilities using softmax

            let max_logit = scaled_logits.iter().max().unwrap();

            var exp_logits: [f32] = [];

            var sum_exp = 0.0;

            

            for logit in scaled_logits {

                let exp_val = exp(logit - max_logit);

                exp_logits.push(exp_val);

                sum_exp += exp_val;

            }

            

            var probs: [f32] = [];

            for exp_val in exp_logits {

                probs.push(exp_val / sum_exp);

            }

            

            // Apply top-p (nucleus) sampling

            let sorted_indices = Self.argsort_descending(&probs);

            var cumulative_prob = 0.0;

            var nucleus_size = 0;

            

            for idx in sorted_indices {

                cumulative_prob += probs[idx];

                nucleus_size += 1;

                if cumulative_prob >= top_p {

                    break;

                }

            }

            

            // Create filtered probability distribution

            var filtered_probs: [f32] = [];

            var filtered_indices: [i32] = [];

            var filtered_sum = 0.0;

            

            for i in 0..nucleus_size {

                let idx = sorted_indices[i];

                filtered_probs.push(probs[idx]);

                filtered_indices.push(idx);

                filtered_sum += probs[idx];

            }

            

            // Renormalize

            for i in 0..filtered_probs.len() {

                filtered_probs[i] /= filtered_sum;

            }

            

            // Sample from filtered distribution

            let random_val = random_f32();

            var cumulative = 0.0;

            var selected_idx = 0;

            

            for i in 0..filtered_probs.len() {

                cumulative += filtered_probs[i];

                if random_val <= cumulative {

                    selected_idx = i;

                    break;

                }

            }

            

            let token_id = filtered_indices[selected_idx];

            let log_prob = log(probs[token_id]);

            

            return SamplingResult {

                token_id: token_id,

                log_probability: log_prob

            };

        }

        

        fn argsort_descending(values: &[f32]) -> [i32] {

            var indices: [i32] = [];

            for i in 0..values.len() {

                indices.push(i);

            }

            

            // Sort indices by values in descending order

            indices.sort_by(|a, b| {

                if values[b] > values[a] {

                    return Ordering.Less;

                } else if values[b] < values[a] {

                    return Ordering.Greater;

                } else {

                    return Ordering.Equal;

                }

            });

            

            return indices;

        }

        

        fn select_best_device(

            devices: [ComputeDevice],

            preference: DevicePreference

        ) -> Result<ComputeDevice, Error> {

            // Filter devices by preference

            let candidates = devices.filter(|d| {

                match preference {

                    DevicePreference.GpuOnly => d.is_gpu(),

                    DevicePreference.CpuOnly => d.is_cpu(),

                    DevicePreference.Any => true,

                    DevicePreference.Specific(arch) => {

                        match (d.architecture, arch) {

                            (DeviceArchitecture.NvidiaCuda(_), DeviceArchitecture.NvidiaCuda(_)) => true,

                            (DeviceArchitecture.AmdRocm(_), DeviceArchitecture.AmdRocm(_)) => true,

                            (DeviceArchitecture.AppleMetal(_), DeviceArchitecture.AppleMetal(_)) => true,

                            (DeviceArchitecture.IntelSycl(_), DeviceArchitecture.IntelSycl(_)) => true,

                            _ => false

                        }

                    }

                }

            });

            

            if candidates.is_empty() {

                return Err(Error.new("No suitable compute device found"));

            }

            

            // Select device with most available memory

            let best_device = candidates.max_by_key(|d| d.available_memory()).unwrap();

            return Ok(best_device);

        }

        

        fn get_metrics(&self) -> SystemMetrics {

            let metrics = self.metrics.lock();

            return metrics.clone();

        }

    }

    

    struct GenerationResult {

        text: string,

        tokens_generated: i32,

        average_log_probability: f64,

        finish_reason: FinishReason

    }

    

    enum FinishReason {

        EndOfSequence,

        MaxTokens,

        Error

    }

    

    struct SamplingResult {

        token_id: i32,

        log_probability: f64

    }

    

    // Local LLM engine implementation

    struct LocalLLMEngine {

        model: TransformerModel,

        tokenizer: Tokenizer,

        device: ComputeDevice,

        batch_size: i32,

        kv_cache_enabled: bool

    }

    

    impl LocalLLMEngine {

        fn new(

            model_path: string,

            device: ComputeDevice,

            batch_size: i32,

            kv_cache_enabled: bool

        ) -> Result<Self, Error> {

            // Load model from file

            let model = TransformerModel.load_from_file(model_path)?;

            

            // Move model to target device

            model.to_device(device);

            

            // Load tokenizer from same directory

            let model_dir = path.dirname(model_path);

            let tokenizer = Tokenizer.load_from_directory(model_dir)?;

            

            return Ok(Self {

                model,

                tokenizer,

                device,

                batch_size,

                kv_cache_enabled

            });

        }

    }

    

    // Remote LLM engine implementation

    struct RemoteLLMEngine {

        endpoint: string,

        api_key: string,

        http_client: HttpClient,

        model_name: string

    }

    

    impl RemoteLLMEngine {

        fn new(endpoint: string, api_key: string, model_name: string) -> Self {

            let http_client = HttpClient.new()

                .with_timeout(Duration.seconds(60))

                .with_retry_policy(RetryPolicy.exponential_backoff(3));

            

            return Self { endpoint, api_key, http_client, model_name };

        }

        

        async fn generate(

            &self,

            prompt: string,

            max_tokens: i32,

            temperature: f32

        ) -> Result<GenerationResult, Error> {

            // Construct API request

            let request_body = json!({

                "model": self.model_name,

                "prompt": prompt,

                "max_tokens": max_tokens,

                "temperature": temperature,

                "top_p": 0.9

            });

            

            // Send request to remote endpoint

            let response = await self.http_client

                .post(self.endpoint + "/v1/completions")

                .header("Authorization", "Bearer " + self.api_key)

                .header("Content-Type", "application/json")

                .json(request_body)

                .send()?;

            

            // Check response status

            if response.status_code() != 200 {

                let error_text = await response.text()?;

                return Err(Error.new("API request failed: " + error_text));

            }

            

            // Parse response

            let response_json = await response.json()?;

            

            let generated_text = response_json["choices"][0]["text"]

                .as_string()

                .ok_or(Error.new("Invalid response format"))?;

            

            let tokens_generated = response_json["usage"]["completion_tokens"]

                .as_i32()

                .unwrap_or(0);

            

            let finish_reason_str = response_json["choices"][0]["finish_reason"]

                .as_string()

                .unwrap_or("unknown");

            

            let finish_reason = match finish_reason_str {

                "stop" => FinishReason.EndOfSequence,

                "length" => FinishReason.MaxTokens,

                _ => FinishReason.Error

            };

            

            return Ok(GenerationResult {

                text: generated_text,

                tokens_generated: tokens_generated,

                average_log_probability: 0.0,

                finish_reason: finish_reason

            });

        }

    }

    

    // Transformer model implementation

    struct TransformerModel {

        config: ModelConfig,

        token_embeddings: EmbeddingLayer,

        position_embeddings: EmbeddingLayer,

        layers: [TransformerLayer],

        output_norm: LayerNorm,

        output_projection: LinearLayer,

        device: ComputeDevice

    }

    

    struct ModelConfig {

        vocab_size: i32,

        hidden_size: i32,

        num_layers: i32,

        num_attention_heads: i32,

        intermediate_size: i32,

        max_position_embeddings: i32,

        layer_norm_epsilon: f32,

        hidden_dropout_prob: f32

    }

    

    impl TransformerModel {

        fn load_from_file(path: string) -> Result<Self, Error> {

            // Open model file

            let file = File.open(path)?;

            let reader = SafeTensorsReader.new(file)?;

            

            // Read model configuration

            let config_json = reader.read_metadata("config")?;

            let config = ModelConfig.from_json(config_json)?;

            

            // Initialize model structure with default device (CPU)

            let default_device = ComputeDevice.cpu();

            var model = Self.new_from_config(config, default_device);

            

            // Load weights for token embeddings

            let token_embed_weight = reader.read_tensor("token_embeddings.weight")?;

            model.token_embeddings.weight = token_embed_weight;

            

            // Load weights for position embeddings

            let pos_embed_weight = reader.read_tensor("position_embeddings.weight")?;

            model.position_embeddings.weight = pos_embed_weight;

            

            // Load weights for each transformer layer

            for i in 0..model.layers.len() {

                let prefix = "layers." + i.to_string();

                

                // Attention weights

                let q_weight = reader.read_tensor(prefix + ".attention.query_proj.weight")?;

                let k_weight = reader.read_tensor(prefix + ".attention.key_proj.weight")?;

                let v_weight = reader.read_tensor(prefix + ".attention.value_proj.weight")?;

                let o_weight = reader.read_tensor(prefix + ".attention.output_proj.weight")?;

                

                model.layers[i].attention.query_proj.weight = q_weight;

                model.layers[i].attention.key_proj.weight = k_weight;

                model.layers[i].attention.value_proj.weight = v_weight;

                model.layers[i].attention.output_proj.weight = o_weight;

                

                // Layer norm weights

                let attn_norm_weight = reader.read_tensor(prefix + ".attention_norm.weight")?;

                let attn_norm_bias = reader.read_tensor(prefix + ".attention_norm.bias")?;

                model.layers[i].attention_norm.weight = attn_norm_weight;

                model.layers[i].attention_norm.bias = attn_norm_bias;

                

                // Feed-forward weights

                let gate_weight = reader.read_tensor(prefix + ".feed_forward.gate_proj.weight")?;

                let up_weight = reader.read_tensor(prefix + ".feed_forward.up_proj.weight")?;

                let down_weight = reader.read_tensor(prefix + ".feed_forward.down_proj.weight")?;

                

                model.layers[i].feed_forward.gate_proj.weight = gate_weight;

                model.layers[i].feed_forward.up_proj.weight = up_weight;

                model.layers[i].feed_forward.down_proj.weight = down_weight;

                

                // FFN layer norm weights

                let ffn_norm_weight = reader.read_tensor(prefix + ".ffn_norm.weight")?;

                let ffn_norm_bias = reader.read_tensor(prefix + ".ffn_norm.bias")?;

                model.layers[i].ffn_norm.weight = ffn_norm_weight;

                model.layers[i].ffn_norm.bias = ffn_norm_bias;

            }

            

            // Load output layer weights

            let output_norm_weight = reader.read_tensor("output_norm.weight")?;

            let output_norm_bias = reader.read_tensor("output_norm.bias")?;

            model.output_norm.weight = output_norm_weight;

            model.output_norm.bias = output_norm_bias;

            

            let output_proj_weight = reader.read_tensor("output_projection.weight")?;

            model.output_projection.weight = output_proj_weight;

            

            return Ok(model);

        }

        

        fn new_from_config(config: ModelConfig, device: ComputeDevice) -> Self {

            // Initialize embeddings

            let token_embeddings = EmbeddingLayer.new(

                config.vocab_size,

                config.hidden_size,

                device

            );

            

            let position_embeddings = EmbeddingLayer.new(

                config.max_position_embeddings,

                config.hidden_size,

                device

            );

            

            // Initialize transformer layers

            var layers: [TransformerLayer] = [];

            for i in 0..config.num_layers {

                let layer = TransformerLayer.new(config, device);

                layers.push(layer);

            }

            

            // Initialize output layers

            let output_norm = LayerNorm.new(config.hidden_size, config.layer_norm_epsilon, device);

            let output_projection = LinearLayer.new(config.hidden_size, config.vocab_size, device);

            

            return Self {

                config,

                token_embeddings,

                position_embeddings,

                layers,

                output_norm,

                output_projection,

                device

            };

        }

        

        fn forward(&self, input_tokens: Tensor) -> Tensor {

            let batch_size = input_tokens.size(0);

            let seq_len = input_tokens.size(1);

            

            // Get token embeddings

            var hidden_states = self.token_embeddings.forward(input_tokens);

            

            // Add position embeddings

            let positions = Tensor.arange(0, seq_len, self.device);

            let position_embeds = self.position_embeddings.forward(positions);

            

            // Broadcast position embeddings across batch

            let position_embeds_expanded = position_embeds.unsqueeze(0).expand(batch_size, seq_len, -1);

            hidden_states = hidden_states + position_embeds_expanded;

            

            // Process through transformer layers

            for layer in &self.layers {

                hidden_states = layer.forward(hidden_states);

            }

            

            // Apply output normalization

            hidden_states = self.output_norm.forward(hidden_states);

            

            // Project to vocabulary size

            let logits = self.output_projection.forward(hidden_states);

            

            return logits;

        }

        

        fn to_device(&mut self, device: ComputeDevice) {

            self.device = device;

            

            self.token_embeddings.to_device(device);

            self.position_embeddings.to_device(device);

            

            for layer in &mut self.layers {

                layer.to_device(device);

            }

            

            self.output_norm.to_device(device);

            self.output_projection.to_device(device);

        }

        

        fn parameter_count(&self) -> i64 {

            var count: i64 = 0;

            

            count += self.token_embeddings.parameter_count();

            count += self.position_embeddings.parameter_count();

            

            for layer in &self.layers {

                count += layer.parameter_count();

            }

            

            count += self.output_norm.parameter_count();

            count += self.output_projection.parameter_count();

            

            return count;

        }

    }

    

    struct TransformerLayer {

        attention: MultiHeadAttention,

        attention_norm: LayerNorm,

        feed_forward: FeedForwardNetwork,

        ffn_norm: LayerNorm

    }

    

    impl TransformerLayer {

        fn new(config: ModelConfig, device: ComputeDevice) -> Self {

            let head_dim = config.hidden_size / config.num_attention_heads;

            

            let attention = MultiHeadAttention.new(

                config.num_attention_heads,

                head_dim,

                config.hidden_size,

                device

            );

            

            let attention_norm = LayerNorm.new(

                config.hidden_size,

                config.layer_norm_epsilon,

                device

            );

            

            let feed_forward = FeedForwardNetwork.new(

                config.hidden_size,

                config.intermediate_size,

                device

            );

            

            let ffn_norm = LayerNorm.new(

                config.hidden_size,

                config.layer_norm_epsilon,

                device

            );

            

            return Self { attention, attention_norm, feed_forward, ffn_norm };

        }

        

        fn forward(&self, input: Tensor) -> Tensor {

            // Self-attention with residual connection

            var hidden = self.attention_norm.forward(input);

            hidden = self.attention.forward(hidden);

            hidden = input + hidden;

            

            // Feed-forward network with residual connection

            var ffn_input = self.ffn_norm.forward(hidden);

            ffn_input = self.feed_forward.forward(ffn_input);

            hidden = hidden + ffn_input;

            

            return hidden;

        }

        

        fn to_device(&mut self, device: ComputeDevice) {

            self.attention.to_device(device);

            self.attention_norm.to_device(device);

            self.feed_forward.to_device(device);

            self.ffn_norm.to_device(device);

        }

        

        fn parameter_count(&self) -> i64 {

            var count: i64 = 0;

            count += self.attention.parameter_count();

            count += self.attention_norm.parameter_count();

            count += self.feed_forward.parameter_count();

            count += self.ffn_norm.parameter_count();

            return count;

        }

    }

    

    struct MultiHeadAttention {

        num_heads: i32,

        head_dim: i32,

        hidden_size: i32,

        query_proj: LinearLayer,

        key_proj: LinearLayer,

        value_proj: LinearLayer,

        output_proj: LinearLayer

    }

    

    impl MultiHeadAttention {

        fn new(num_heads: i32, head_dim: i32, hidden_size: i32, device: ComputeDevice) -> Self {

            let qkv_size = num_heads * head_dim;

            

            let query_proj = LinearLayer.new(hidden_size, qkv_size, device);

            let key_proj = LinearLayer.new(hidden_size, qkv_size, device);

            let value_proj = LinearLayer.new(hidden_size, qkv_size, device);

            let output_proj = LinearLayer.new(qkv_size, hidden_size, device);

            

            return Self {

                num_heads,

                head_dim,

                hidden_size,

                query_proj,

                key_proj,

                value_proj,

                output_proj

            };

        }

        

        fn forward(&self, input: Tensor) -> Tensor {

            let batch_size = input.size(0);

            let seq_len = input.size(1);

            

            // Project input to query, key, and value

            let queries = self.query_proj.forward(input);

            let keys = self.key_proj.forward(input);

            let values = self.value_proj.forward(input);

            

            // Reshape to separate heads: [batch, seq, heads, head_dim]

            let queries = queries.reshape(batch_size, seq_len, self.num_heads, self.head_dim);

            let keys = keys.reshape(batch_size, seq_len, self.num_heads, self.head_dim);

            let values = values.reshape(batch_size, seq_len, self.num_heads, self.head_dim);

            

            // Transpose to [batch, heads, seq, head_dim]

            let queries = queries.transpose(1, 2);

            let keys = keys.transpose(1, 2);

            let values = values.transpose(1, 2);

            

            // Compute attention scores: [batch, heads, seq, seq]

            let scale = 1.0 / sqrt(self.head_dim as f32);

            var attention_scores = queries.matmul(keys.transpose(-2, -1));

            attention_scores = attention_scores * scale;

            

            // Apply causal mask

            let causal_mask = self.create_causal_mask(seq_len, input.device);

            attention_scores = attention_scores + causal_mask;

            

            // Convert scores to probabilities

            let attention_probs = softmax(attention_scores, dim: -1);

            

            // Apply attention to values: [batch, heads, seq, head_dim]

            var output = attention_probs.matmul(values);

            

            // Transpose back to [batch, seq, heads, head_dim]

            output = output.transpose(1, 2);

            

            // Reshape to [batch, seq, hidden_size]

            output = output.reshape(batch_size, seq_len, self.num_heads * self.head_dim);

            

            // Final output projection

            output = self.output_proj.forward(output);

            

            return output;

        }

        

        fn create_causal_mask(&self, seq_len: i32, device: ComputeDevice) -> Tensor {

            var mask_data: [f32] = [];

            

            for i in 0..seq_len {

                for j in 0..seq_len {

                    if j > i {

                        mask_data.push(f32.neg_infinity());

                    } else {

                        mask_data.push(0.0);

                    }

                }

            }

            

            return Tensor.from_slice(mask_data, [seq_len, seq_len], device);

        }

        

        fn to_device(&mut self, device: ComputeDevice) {

            self.query_proj.to_device(device);

            self.key_proj.to_device(device);

            self.value_proj.to_device(device);

            self.output_proj.to_device(device);

        }

        

        fn parameter_count(&self) -> i64 {

            var count: i64 = 0;

            count += self.query_proj.parameter_count();

            count += self.key_proj.parameter_count();

            count += self.value_proj.parameter_count();

            count += self.output_proj.parameter_count();

            return count;

        }

    }

    

    struct FeedForwardNetwork {

        gate_proj: LinearLayer,

        up_proj: LinearLayer,

        down_proj: LinearLayer

    }

    

    impl FeedForwardNetwork {

        fn new(hidden_size: i32, intermediate_size: i32, device: ComputeDevice) -> Self {

            let gate_proj = LinearLayer.new(hidden_size, intermediate_size, device);

            let up_proj = LinearLayer.new(hidden_size, intermediate_size, device);

            let down_proj = LinearLayer.new(intermediate_size, hidden_size, device);

            

            return Self { gate_proj, up_proj, down_proj };

        }

        

        fn forward(&self, input: Tensor) -> Tensor {

            // Gated linear unit activation

            let gate = self.gate_proj.forward(input);

            let gate_activated = silu(gate);

            

            let up = self.up_proj.forward(input);

            

            let gated = gate_activated * up;

            

            let output = self.down_proj.forward(gated);

            

            return output;

        }

        

        fn to_device(&mut self, device: ComputeDevice) {

            self.gate_proj.to_device(device);

            self.up_proj.to_device(device);

            self.down_proj.to_device(device);

        }

        

        fn parameter_count(&self) -> i64 {

            var count: i64 = 0;

            count += self.gate_proj.parameter_count();

            count += self.up_proj.parameter_count();

            count += self.down_proj.parameter_count();

            return count;

        }

    }

    

    struct LinearLayer {

        weight: Tensor,

        bias: Option<Tensor>,

        in_features: i32,

        out_features: i32,

        device: ComputeDevice

    }

    

    impl LinearLayer {

        fn new(in_features: i32, out_features: i32, device: ComputeDevice) -> Self {

            let weight = Tensor.new([out_features, in_features], DataType.Float32, device);

            

            return Self {

                weight,

                bias: None,

                in_features,

                out_features,

                device

            };

        }

        

        fn forward(&self, input: Tensor) -> Tensor {

            // Matrix multiplication: input @ weight.T

            let output = input.matmul(self.weight.transpose(-2, -1));

            

            // Add bias if present

            if let Some(bias) = &self.bias {

                return output + bias;

            } else {

                return output;

            }

        }

        

        fn to_device(&mut self, device: ComputeDevice) {

            self.device = device;

            self.weight = self.weight.to_device(device);

            if let Some(bias) = &self.bias {

                self.bias = Some(bias.to_device(device));

            }

        }

        

        fn parameter_count(&self) -> i64 {

            var count = (self.in_features as i64) * (self.out_features as i64);

            if self.bias.is_some() {

                count += self.out_features as i64;

            }

            return count;

        }

    }

    

    struct LayerNorm {

        weight: Tensor,

        bias: Tensor,

        normalized_shape: i32,

        epsilon: f32,

        device: ComputeDevice

    }

    

    impl LayerNorm {

        fn new(normalized_shape: i32, epsilon: f32, device: ComputeDevice) -> Self {

            let weight = Tensor.ones([normalized_shape], DataType.Float32, device);

            let bias = Tensor.zeros([normalized_shape], DataType.Float32, device);

            

            return Self { weight, bias, normalized_shape, epsilon, device };

        }

        

        fn forward(&self, input: Tensor) -> Tensor {

            // Compute mean and variance along last dimension

            let mean = input.mean(dim: -1, keepdim: true);

            let variance = input.var(dim: -1, keepdim: true);

            

            // Normalize

            let normalized = (input - mean) / sqrt(variance + self.epsilon);

            

            // Scale and shift

            let output = normalized * self.weight + self.bias;

            

            return output;

        }

        

        fn to_device(&mut self, device: ComputeDevice) {

            self.device = device;

            self.weight = self.weight.to_device(device);

            self.bias = self.bias.to_device(device);

        }

        

        fn parameter_count(&self) -> i64 {

            return (self.normalized_shape as i64) * 2;

        }

    }

    

    struct EmbeddingLayer {

        weight: Tensor,

        num_embeddings: i32,

        embedding_dim: i32,

        device: ComputeDevice

    }

    

    impl EmbeddingLayer {

        fn new(num_embeddings: i32, embedding_dim: i32, device: ComputeDevice) -> Self {

            let weight = Tensor.new(

                [num_embeddings, embedding_dim],

                DataType.Float32,

                device

            );

            

            return Self { weight, num_embeddings, embedding_dim, device };

        }

        

        fn forward(&self, indices: Tensor) -> Tensor {

            // Gather embeddings for given indices

            return self.weight.index_select(0, indices);

        }

        

        fn to_device(&mut self, device: ComputeDevice) {

            self.device = device;

            self.weight = self.weight.to_device(device);

        }

        

        fn parameter_count(&self) -> i64 {

            return (self.num_embeddings as i64) * (self.embedding_dim as i64);

        }

    }

    

    // Activation functions

    fn softmax(input: Tensor, dim: i32) -> Tensor {

        let max_vals = input.max(dim: dim, keepdim: true);

        let exp_vals = (input - max_vals).exp();

        let sum_exp = exp_vals.sum(dim: dim, keepdim: true);

        return exp_vals / sum_exp;

    }

    

    fn silu(input: Tensor) -> Tensor {

        // SiLU activation: x * sigmoid(x)

        return input * sigmoid(input);

    }

    

    fn sigmoid(input: Tensor) -> Tensor {

        return 1.0 / (1.0 + (-input).exp());

    }

    

    // SafeTensors file reader

    struct SafeTensorsReader {

        file: File,

        header: SafeTensorsHeader,

        data_offset: usize

    }

    

    struct SafeTensorsHeader {

        tensors: HashMap<string, TensorMetadata>,

        metadata: HashMap<string, string>

    }

    

    struct TensorMetadata {

        dtype: string,

        shape: [i32],

        data_offsets: (usize, usize)

    }

    

    impl SafeTensorsReader {

        fn new(file: File) -> Result<Self, Error> {

            // Read header size (first 8 bytes)

            var header_size_bytes: [u8; 8] = [0; 8];

            file.read_exact(&mut header_size_bytes)?;

            let header_size = u64.from_le_bytes(header_size_bytes) as usize;

            

            // Read header JSON

            var header_bytes: [u8] = vec![0; header_size];

            file.read_exact(&mut header_bytes)?;

            let header_json = string.from_utf8(header_bytes)?;

            

            // Parse header

            let header = SafeTensorsHeader.from_json(header_json)?;

            

            let data_offset = 8 + header_size;

            

            return Ok(Self { file, header, data_offset });

        }

        

        fn read_tensor(&self, name: string) -> Result<Tensor, Error> {

            let metadata = self.header.tensors.get(name)

                .ok_or(Error.new("Tensor not found: " + name))?;

            

            // Seek to tensor data

            let (start_offset, end_offset) = metadata.data_offsets;

            let absolute_offset = self.data_offset + start_offset;

            self.file.seek(SeekFrom.Start(absolute_offset))?;

            

            // Read tensor data

            let data_size = end_offset - start_offset;

            var data_bytes: [u8] = vec![0; data_size];

            self.file.read_exact(&mut data_bytes)?;

            

            // Convert to tensor

            let dtype = Self.parse_dtype(metadata.dtype)?;

            let tensor = Tensor.from_bytes(data_bytes, metadata.shape.clone(), dtype);

            

            return Ok(tensor);

        }

        

        fn read_metadata(&self, key: string) -> Result<string, Error> {

            self.header.metadata.get(key)

                .ok_or(Error.new("Metadata key not found: " + key))

                .map(|v| v.clone())

        }

        

        fn parse_dtype(dtype_str: string) -> Result<DataType, Error> {

            match dtype_str.as_str() {

                "F32" => Ok(DataType.Float32),

                "F16" => Ok(DataType.Float16),

                "I32" => Ok(DataType.Int32),

                "I64" => Ok(DataType.Int64),

                "U8" => Ok(DataType.UInt8),

                _ => Err(Error.new("Unknown dtype: " + dtype_str))

            }

        }

    }

    

    // Example usage and main entry point

    fn main() -> Result<(), Error> {

        // Configure the inference system

        let config = InferenceSystemConfig {

            local_model_path: Some("/models/llama-3-8b.safetensors"),

            remote_endpoint: Some("https://api.openai.com"),

            remote_api_key: Some("sk-..."),

            device_preference: DevicePreference.Any,

            max_batch_size: 8,

            max_context_length: 4096,

            enable_kv_cache: true,

            log_level: LogLevel.Info

        };

        

        // Initialize the inference system

        let system = InferenceSystem.new(config)?;

        

        // Create async runtime

        let runtime = Runtime.new()?;

        

        // Run inference using local model

        let result_local = runtime.block_on(async {

            await system.generate(

                "Explain quantum computing in simple terms:",

                max_tokens: 200,

                temperature: 0.7,

                top_p: 0.9,

                use_local: true

            )

        })?;

        

        println("Local generation result:");

        println(result_local.text);

        println("Tokens generated: " + result_local.tokens_generated.to_string());

        println("Finish reason: " + result_local.finish_reason.to_string());

        println("");

        

        // Run inference using remote API

        let result_remote = runtime.block_on(async {

            await system.generate(

                "What are the benefits of renewable energy?",

                max_tokens: 150,

                temperature: 0.8,

                top_p: 0.95,

                use_local: false

            )

        })?;

        

        println("Remote generation result:");

        println(result_remote.text);

        println("Tokens generated: " + result_remote.tokens_generated.to_string());

        println("");

        

        // Display system metrics

        let metrics = system.get_metrics();

        println("System Metrics:");

        println("Total requests: " + metrics.total_requests.to_string());

        println("Total tokens generated: " + metrics.total_tokens_generated.to_string());

        println("Average latency: " + metrics.average_latency_ms.to_string() + " ms");

        println("GPU memory used: " + (metrics.gpu_memory_used_bytes / (1024 * 1024)).to_string() + " MB");

        

        return Ok(());

    }



CONCLUSION


Nexus represents a comprehensive solution to the challenge of building software systems that span the entire spectrum from embedded devices to large-scale enterprise infrastructure. By providing a unified programming model with carefully designed abstractions, the language enables developers to write code once and deploy it across diverse hardware platforms and deployment environments.


The language's support for multiple GPU architectures through a unified abstraction layer is particularly valuable in the current era of heterogeneous computing. Developers can write GPU-accelerated code without being locked into a specific vendor's ecosystem, and their applications can automatically adapt to whatever hardware is available at runtime.


The integration of local and remote LLM inference capabilities demonstrates how Nexus can bridge different deployment models within a single coherent framework. Applications can seamlessly switch between local and remote inference based on resource availability, latency requirements, and cost considerations.


The combination of zero-cost abstractions, flexible memory management, sophisticated concurrency primitives, and comprehensive standard libraries makes Nexus suitable for building production systems that are both performant and maintainable. The language's emphasis on explicitness and compile-time safety helps prevent entire classes of bugs while still providing the low-level control necessary for systems programming.


As software systems continue to grow in complexity and span an ever-wider range of deployment targets, languages like Nexus that can unify these diverse requirements will become increasingly important. The ability to use a single language, toolchain, and set of libraries across the entire stack reduces cognitive load, improves code reuse, and enables more efficient development processes.