Simple Language

Simple is a self-hosted language and toolchain that combines a readable Python-like surface with compiler-integrated testing, documentation, architecture rules, and baremetal-oriented execution paths.

The repo is unusually broad: language, compiler, interpreter, loader, test runner, doc generation, traceability tooling, SDN-backed project databases, editor tooling, and hardware-oriented test flows all live together.

Quick Navigation: Distinctive Features | Feature Status | Quick Start | Language Basics | Examples | Editor Plugins | Documentation

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Distinctive Features

• Self-hosted staged toolchain: real source layers for frontend, type analysis, borrow checking, backend, driver, interpreter, and loader live in-tree.
• Verification-native workflow: SSpec tests, the SPipe runner/docgen process, SDoctest executable docs, coverage, traceability checks, and generated spec docs are part of the toolchain rather than bolted on.
• MDSOC architecture support: virtual capsules, manifests, and architecture-aware repository structure are first-class concepts.
• Parser-friendly macro system: macro definitions, expansion, validation, and hygiene are compiler features rather than editor-hostile text substitution.
• Math-oriented syntax blocks: m{}, loss{}, and nograd{} are implemented syntax with parsing, evaluation, five rendering backends (text, debug, Unicode, LaTeX, Markdown), and editor integration (query/LSP hover, VSCode highlighting/preview, Neovim inline Unicode preview with conceal). The autograd path is complete for the promoted torch-backed C/LLVM scope.
• SDN-backed textual databases: tests, todos, dashboards, and other project metadata are stored through repo-native SDN data flows.
• Multiple execution paths: interpreter, loader, SMF/module loading, and native/LLVM-oriented compilation paths coexist in one system.
• Baremetal-oriented build and test plumbing: QEMU, semihosting, MMIO mailbox, remote baremetal flows, and adapter-backed hardware lanes (8 authoritative) are built into the repo story.
• Tooling-aware language rules: Tree-sitter integration, primitive-public-API linting, traceability tooling, and language statistics are part of the platform.
• Shared UI contract across supported surfaces: one HTTP-based test protocol (Protocol V1) with UITestClient drives both the web backend and the TUI-web proxy through a shared handle_test_request handler, verified by a cross-surface contract suite. Contract: doc/04_architecture/shared_ui_contract.md

Feature Status Highlights

Implemented and safe to advertise:

• SSpec tests, SPipe runner/docgen, SDoctest, coverage, traceability checks, and generated spec docs
• SPipe mock policy: system-test mock ban, HAL-only and custom pattern modes
• Self-hosted staged compiler, interpreter, and loader architecture
• MDSOC manifests and architecture-focused project structure
• Parser-friendly macros with validation and hygiene
• Tree-sitter outline/query tooling
• SDN-backed project, test, and todo databases
• Primitive-public-API linting and semantic wrapper/unit-type patterns
• Borrow-checking infrastructure
• Watch mode and auto-build support
• mmap-backed loader support and executable-memory plumbing
• Baremetal build/test plumbing and host-aware remote baremetal flows
• C/C++ bidirectional SFFI for the supported ABI subset: exports, imports, callback trampolines, layout verification, and round-trip proof tests

Implemented, but best described with qualifiers:

• LLVM full-family closure is complete for the declared public matrix: every llvm-lib and llvm backend row is now explicitly stable or unsupported, with no ambiguous middle states. rust-llvm remains a bootstrap-only seed path outside the public family claim
• Lean verification workflow is complete for the supported verification subset: deterministic Lean generation, proof artifact inventory, Lean/Lake checking, cache invalidation, and verification-state reporting. Contract: doc/04_architecture/lean_verification_contract.md. Report: doc/09_report/lean_verification_complete_2026-04-04.md
• GC and no-GC runtime families: 5 public families (common, nogc_sync_mut, nogc_async_mut, gc_async_mut, nogc_async_mut_noalloc) with compiler boundary enforcement, interpreter warnings, and target preset mapping. Support matrix: doc/04_architecture/runtime_family_support_matrix.md
• Shared UI contract across web backend and TUI-web proxy (Protocol V1): shared handler, structured error model, stable element IDs, cross-surface contract suite — but this is a shared test protocol, not a full unified UI rendering layer
• Remote baremetal execution has 8 authoritative lanes (3 stable + 5 host-aware including both GHDL semihost and mailbox simulation), but hardware-dependent lanes remain host- and board-aware rather than universally complete. Lane matrix: doc/08_tracking/lane_matrix.md

Implemented with bounded scope:

• m{} / loss{} / nograd{} are complete for the promoted torch-backed C/LLVM scope, including backward, detached-input failure, and nograd{} restore semantics. Other backends remain deferred
• AOP provides predicate-based pointcuts (execution, within, attr), deterministic before/after/around advice, compile-time weaving as the default backend, and scoped runtime interception. Support matrix: doc/05_design/aop_support_matrix.md
• VHDL backend compiles a documented hardware-oriented Simple subset to synthesizable VHDL-2008, validated through GHDL analysis/elaboration. Strict fail-fast on unsupported constructs. Two GHDL RV32 simulation lanes are operational: semihost (GDB-backed, ARM semihosting traps) and mailbox (debugger-independent, MMIO at 0x80FF0000 with ram_sentinel result collection). Support matrix: doc/04_architecture/vhdl_support_matrix.md. Mailbox protocol: doc/04_architecture/ghdl_rv32_mailbox_protocol.md

Implemented:

• Anti-dummy / anti-stub enforcement is active on the primary source and compiled CLI surfaces (simple lint, simple verify quality). All public-facing proof suites (SFFI, T32 hardware, compiler/runtime/system) now pass the gate. Remaining debt is only in deferred OS/GPU/experimental areas — all active surfaces are clean.

See doc/report/unique_features.md for the evidence-backed audit.

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Runtime Families

Simple organizes its standard library into runtime families based on allocation, mutation, and concurrency requirements:

Family	Allocation	Mutation	Async	Use Case
common	heap (default)	immutable	no	Pure functions, math, text, encoding
nogc_sync_mut	heap/arena/pool	mutable	no	File I/O, networking, FFI, databases
nogc_async_mut	heap	mutable	yes	Async I/O, threads, actors, generators
gc_async_mut	GC-managed	mutable	yes	GPU/CUDA, ML pipelines
nogc_async_mut_noalloc	stack only	mutable	yes	Baremetal, embedded, RTOS

The compiler enforces family boundaries: importing a GC module from a no-GC context produces a diagnostic warning. Target presets (Baremetal, Hosted, EmbeddedWithHeap) automatically restrict module resolution to compatible families.

For advanced use: nogc_async_immut provides persistent data structures with lock-free concurrency.

See Runtime Family Support Matrix for full contracts, and Known Limitations for current caveats.

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Quick Start

Installation

What you get:

• Complete Simple compiler and toolchain source
• Standard library and generated spec manuals
• Development tools, including MCP server, LSP, and debugger surfaces

Use a source checkout for the current beta. It also initializes the example and tooling submodules used by the docs and tests:

git clone --recurse-submodules https://github.com/ormastes/simple.git
cd simple
export PATH="$PWD/bin:$PATH"
simple --version

For an existing checkout:

git submodule sync --recursive
git submodule update --init --recursive

Note: Rust remains present as the bootstrap seed and host substrate. Product compiler, library, and tool work should stay in Simple source wherever the repo can express it; do not read "pure Simple" as "there is no Rust source in this checkout" today.

Source Footprint

Snapshot generated 2026-04-23 from existing tracked .spl, .rs, .c, .h, .s, .S, and .asm files. Blank lines and comment-only lines are excluded; examples/ code is included; vendored and third-party source is excluded.

Language	Files	Non-comment LOC	src/ LOC	examples/ LOC	test/ LOC	Other LOC
Simple	13,286	1,780,334	887,121	158,796	712,254	22,163
Rust	1,633	411,106	409,852	11	0	1,243
C	158	73,854	14,953	58,859	36	6
Assembly	60	4,758	1,554	3,173	31	0
Total	15,137	2,270,052	1,313,480	220,839	712,321	23,412

From Source (Developers Only)

Only needed if you want to modify the runtime:

scripts/setup/setup.shs
bin/simple build bootstrap

Direct commands behind the wrapper:

src/compiler_rust/target/bootstrap/simple --version
bin/simple build bootstrap
sha256sum bootstrap/simple_stage2 bootstrap/simple_stage3

See doc/02_requirements/app/build/bootstrap.md and doc/03_plan/compiler/bootstrap/pure_simple_bootstrap_stage2_remaining_2026-05-04.md for the current bootstrap flow and remaining pure-Simple self-hosting notes.

Build with GPU Support

simple build --release --features=vulkan

Your First Program

# hello.spl
>>> fn main() -> i64:
...     0  # Entry point, returns exit code

# Run it
simple hello.spl
echo $?  # Prints: 0

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CLI Usage

The simple command works like Python:

Usage:
  simple                      Start interactive REPL
  simple <file.spl>           Run source file
  simple <file.smf>           Run compiled binary
  simple -c "code"            Run code string; statement snippets print only program output
  simple compile <src> [-o <out>]  Compile to SMF
  simple watch <file.spl>     Watch and auto-recompile

Build System (Self-Hosting):
  simple build                Build the project (debug)
  simple build --release      Release build (optimized)
  simple build --bootstrap    Bootstrap build (minimal 9.3MB)
  simple build test           Run all tests
  simple build coverage       Generate coverage reports
  simple build lint           Run linter (clippy)
  simple build fmt            Format code (rustfmt)
  simple build check          Run all quality checks
  simple build clean          Clean build artifacts
  simple build --help         Show all build options

Options:
  -h, --help     Show help
  -v, --version  Show version
  -c <code>      Run code string
  --gc-log       Enable verbose GC logging
  --gc=off       Disable garbage collection

Examples

# Interactive REPL
simple
>>> 1 + 2
3
>>> x = 10
>>> x * 5
50
>>> exit

# Run a program
echo "main = 42" > hello.spl
simple hello.spl
echo $?  # Exit code: 42

# Compile to binary
simple compile hello.spl
simple hello.smf  # Run the compiled binary

# Watch mode (auto-recompile on changes)
simple watch app.spl

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Language Basics

Variables & Types

# Variables - immutable by default, mutable with var
>>> x = 10
>>> x
10
>>> var y = 20
>>> y
20
>>> PI = 3.14159
>>> PI
3.14159

# Type inference works automatically
>>> count = 100
>>> count
100

# Basic types inferred
>>> a = 42
>>> a
42
>>> pi = 3.14159
>>> flag = true
>>> flag
true

# String interpolation default
>>> name = "world"
>>> msg = "Hello, {name}!"
>>> print msg
Hello, world!

Control Flow

# If/else with indentation
>>> var x = 5
>>> if x > 0:
...     print "positive"
... elif x < 0:
...     print "negative"
... else:
...     print "zero"
positive

# Loops
>>> for i in 0..3:
...     print i
0
1
2

>>> while x > 3:
...     x = x - 1
>>> x
3

Functions

>>> fn add(a: i64, b: i64) -> i64:
...     a + b  # Implicit return

>>> fn greet(greeting: text):
...     print "Hello, {greeting}!"

# Function calls
>>> sum = add(1, 2)
>>> sum
3
>>> greet("Alice")
Hello, Alice!

# Lambdas with backslash
>>> double = \x: x * 2
>>> nums = [1, 2, 3, 4, 5]
>>> evens = nums.filter(\x: x % 2 == 0)
>>> evens
[2, 4]

Structs & Classes

# Structs (value types)
struct Point:
    x: f64
    y: f64

p = Point(x: 1.0, y: 2.0)

# Classes (reference types)
class Person:
    name: text
    age: i64

    fn greet():
        print "Hi, {self.name}!"

alice = Person(name: "Alice", age: 30)
alice.greet()

Collections

# Arrays - short form (no val)
>>> nums = [1, 2, 3, 4, 5]
>>> first = nums[0]
>>> first
1

# Collection methods
>>> count = nums.len()
>>> count
5

# Dictionary (short form)
>>> scores = {"alice": 100, "bob": 85}
>>> alice_score = scores["alice"]
>>> alice_score
100

# Filter with lambda
>>> odds = nums.filter(\x: x % 2 == 1)
>>> odds
[1, 3, 5]
>>> big_nums = nums.filter(\x: x > 3)
>>> big_nums
[4, 5]

# Tuples
>>> pair = (1, "hello")
>>> num = pair.0
>>> num
1
>>> msg = pair.1
>>> msg
"hello"

# List comprehensions
>>> squared = [x * x for x in 0..5]
>>> squared
[0, 1, 4, 9, 16]
>>> evens = [x for x in nums if x % 2 == 0]
>>> evens
[2, 4]

Unit Types (Postfix Literals)

Type-safe units prevent mixing incompatible values:

# Define measurement unit families with postfix syntax
unit length(base: f64):
    mm = 0.001, cm = 0.01, m = 1.0, km = 1000.0

unit velocity(base: f64) = length / time:
    mps = 1.0, kmph = 0.2777777777777778, mph = 0.44704
# The standards-backed catalog records km/h canonically as kilometre / hour
# with exact factor 5/18 relative to m/s.

# Define nominal wrappers with postfix syntax
newunit UserId: i64 as uid
newunit OrderId: i64 as oid

# Usage with postfix literals
height = 175_cm              # Length type
width = 10_cm + 5_mm         # Auto-converts to same base
speed = 200_kmph             # Velocity type
distance = 42_km             # Length type

# Type safety - compile error:
# bad = height + speed       # Error: can't add Length + Velocity

# Semantic IDs prevent mix-ups
user = 42_uid                # UserId
order = 100_oid              # OrderId
# wrong: UserId = 100_oid    # Error: OrderId ≠ UserId

# Computed units
travel_time = distance / speed    # Returns Time type
print("ETA: {travel_time.to_min()} minutes")

Pattern Matching

enum Shape:
    Circle(radius: f64)
    Rectangle(width: f64, height: f64)
    Square(side: f64)
    Triangle(base: f64, height: f64)

# Pattern matching with case syntax
fn area(s: Shape) -> f64:
    match s:
        case Circle(r):
            3.14159 * r * r  # Implicit return
        case Rectangle(w, h):
            w * h
        case Square(side):
            side * side
        case Triangle(b, h):
            0.5 * b * h

# Preferred arrow syntax (shorter)
fn perimeter(s: Shape) -> f64:
    match s:
        | Circle(r) -> 2.0 * 3.14159 * r
        | Rectangle(w, h) -> 2.0 * (w + h)
        | Square(side) -> 4.0 * side
        | Triangle(a, b, c) -> a + b + c

# Pattern matching with nil (not None)
fn get_radius(opt: Option<f64>) -> f64:
    match opt:
        | Some(r) -> r
        | nil -> 0.0  # Use nil instead of None

Parser-Friendly Macros

Simple macros are contract-first and LL(1) parseable - the IDE can provide autocomplete without expanding the macro:

# Macro declares what it introduces in the contract header
macro define_counter(NAME: Str const) -> (
  returns result: (init: Int, step: Int),
  intro counter_fn: enclosing.class.fn "{NAME}Counter"(start: Int) -> Int
):
  const_eval:
    const init = 0
    const step = 1

  emit counter_fn:
    fn "{NAME}Counter"(start: Int) -> Int:
      start + step

# Usage - IDE knows about UserCounter before expansion
class Demo:
  define_counter!("User")

  fn run() -> Int:
    self.UserCounter(10)  # Autocomplete works!

Built-in macros:

# Print with formatting
println!("Hello, {name}!")           # Print with newline
print!("Value: {x}")                 # Print without newline

# Debug output with source location
dbg!(expression)                     # Prints: [file:line] expression = value

# Assertions
assert!(condition)                   # Panic if false
assert_eq!(a, b)                     # Panic if a != b
assert_ne!(a, b)                     # Panic if a == b

# Collections
nums = vec![1, 2, 3, 4, 5]           # Create vector
formatted = format!("x={x}")         # Format string without printing

# Panic with message
panic!("Something went wrong: {err}")

Const-unrolled macro (generate multiple functions):

# Generate accessor functions for each axis
macro gen_axes(BASE: Str const, N: Int const) -> (
  intro axes:
    for i in 0 .. N:
      enclosing.class.fn "{BASE}{i}"(v: Vec[N]) -> Int
):
  emit axes:
    for i in 0 .. N:
      fn "{BASE}{i}"(v: Vec[N]) -> Int:
        v[i]

# Usage: generates x(), y(), z() accessors
class Point3D:
  gen_axes!("axis_", 3)  # Creates axis_0, axis_1, axis_2

AOP & Aspect-Oriented Programming

Predicate-based pointcuts with compile-time weaving as the default execution model:

# Before advice — runs before matching functions
on pc{ execution(* handle_request(..)) } use log_entry before priority 10

# After advice — runs after successful return
on pc{ execution(* save(..)) & attr(audited) } use audit_write after_success priority 20

# Around advice — wraps function with proceed() contract
on pc{ within(services.*) } use trace_around around priority 50

# Architecture rules — enforce layer dependencies at compile time
forbid pc{ within(hal.*) } "HAL cannot depend on services"
allow  pc{ within(services.*) } "Services can use HAL"

Supported selectors: execution(*), within(*), attr(*) with & (AND), | (OR), ! (NOT) operators. Advice kinds: before, after_success, after_error, around (proceed exactly-once). Ordering: priority (descending) > specificity > lexicographic name. Zero overhead: no weaving metadata when no aspects are defined. Runtime interception: scoped, opt-in only, disabled in release builds.

See AOP Support Matrix for the full contract.

SDN Configuration

Simple Data Notation - a minimal, token-efficient format for config files:

# app.sdn - Application configuration
app:
    name: MyService
    version: 2.1.0

server:
    host: 0.0.0.0
    port: 8080
    workers: 4

# Inline arrays and dicts
features = [auth, logging, metrics]
database = {driver: postgres, host: localhost, port: 5432}

# Named tables - compact tabular data
rate_limits |endpoint, requests, window|
    /api/login, 5, 60
    /api/search, 100, 60
    /api/upload, 10, 300

Load SDN in Simple:

config = sdn::load("app.sdn")
print("Server port: {config.server.port}")

SDoctest

Executable examples are part of the maintained test surface. Simple supports both demonstration blocks and verified sdoctest blocks, with sdoctest intended for examples that must run and match output.

>>> factorial(5)
120
>>> factorial(0)
1

## Stack data structure with LIFO semantics
struct Stack:
    items: [i64]

var s = Stack(items: [])
s.items.push(1)
s.items.push(2)
print s.items.len()  # 2

Run SDoctest examples:

simple test --sdoctest README.md      # Run verified examples in Markdown/docs
simple test --sdoctest src/math.spl   # Run file-local doctest examples
simple test --sdoctest --tag slow     # Filter by tag

--doctest is still accepted as a compatibility alias, but --sdoctest is the clearer name for the implemented path.

Functional Update Operator (->)

# The -> operator calls a method and assigns result back
var data = load_data()
data->normalize()        # data = data.normalize()
data->filter(min: 0)     # data = data.filter(min: 0)

# Chaining
data->normalize()->filter(min: 0)->save("out.txt")

GPU Computing

import std.gpu

# GPU kernel style 1: #[gpu] with explicit bounds check
#[gpu]
fn vector_add_kernel(a: []f32, b: []f32, result: []f32):
    idx = gpu.global_id(0)           # Global thread index
    if idx < len(result):
        result[idx] = a[idx] + b[idx]

# GPU kernel style 2: @simd with auto bounds handling
@simd
fn vector_scale(data: []f32, scale: f32):
    val i = this.index()             # Global linear index (same as gpu.global_id())
    data[i] = data[i] * scale        # Bounds auto-handled

# Host function - runs on CPU
fn main():
    device = gpu.Device()

    # Allocate and upload data
    a = [1.0, 2.0, 3.0, 4.0]
    b = [5.0, 6.0, 7.0, 8.0]

    buf_a = device.alloc_buffer(a)
    buf_b = device.alloc_buffer(b)
    buf_result = device.alloc_buffer<f32>(4)

    # Launch kernel
    device.launch_1d(vector_add_kernel, [buf_a, buf_b, buf_result], 4)

    # Download results
    device.sync()
    result = device.download(buf_result)
    # result = [6.0, 8.0, 10.0, 12.0]

GPU Thread Indexers:

#[gpu]
fn matrix_multiply(A: []f32, B: []f32, C: []f32, N: u32):
    # Multi-dimensional indexing
    val row = gpu.global_id(0)       # First dimension
    val col = gpu.global_id(1)       # Second dimension

    # Thread group (workgroup) info
    val local_row = gpu.local_id(0)  # Index within workgroup
    val group_row = gpu.group_id(0)  # Workgroup index

    # Alternative @simd style
    # val(row, col) = this.index()  # Tuple for 2D
    # vallocal_idx = this.thread_index()
    # valgroup_idx = this.group_index()

    if row < N and col < N:
        var sum = 0.0_f32
        for k in 0..N:
            sum += A[row * N + k] * B[k * N + col]
        C[row * N + col] = sum

GPU Examples: See examples/gpu/vulkan/ for vector add, matrix multiply, reduction, and image blur.

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Documentation

Quick Links by Topic

Topic	Description	Link
Docs Hub	Numbered documentation index	doc/README.md
Language Spec	Executable and generated specs	doc/06_spec/README.md
Guides	Practical how-to guides	doc/07_guide/README.md
Plans	Implementation roadmap	doc/03_plan/README.md
Research	Design explorations	doc/01_research/README.md
Architecture	System design principles	doc/04_architecture/README.md
Tracking	Bugs, tests, and todo tracking	doc/08_tracking/README.md
Reports	Session and milestone reports	doc/09_report/README.md
Deep Learning	Neural networks and GPU computing	doc/07_guide/deep_learning/deep_learning.md

Core Documentation

Getting Started:

• Documentation Hub - Current entry point for the numbered doc tree
• Getting Started - Project setup and first steps
• Syntax Quick Reference - Canonical public syntax cheat sheet
• Testing Guide - Testing workflow and command surface

Language Reference:

• Syntax Guide - Surface syntax and examples
• Type System Guide - Types, mutability, and usage
• Module System Guide - Imports, packages, and layout
• Standard Library Guide - Stdlib organization and usage

GPU Computing:

• Deep Learning Guide - Pure Simple, model-oriented, and training flows
• GPU Programming Guide - Backend and kernel-oriented GPU usage
• GPU API - API-level GPU reference
• LLVM Backend Architecture - Backend implementation details

Development:

• Build Guide - Building Simple and common workflows
• Testing Guide - Test runner behavior and flags
• SSpec Scenario Manual Guide - step(...), inline scenarios, capture, and generated manual style
• Mock Policy Guide - System test mock ban and test level enforcement
• Coverage Guide - Coverage, SDoctest, and enforcement
• MCP Tooling Guide - MCP registration and usage

Advanced Features:

• Macro System - Executable macro spec and status
• AOP Support Matrix - Supported selectors, advice kinds, backends, and error codes
• SDN Format - Note/SDN storage and indexing format
• SDoctest - Documentation testing and verified examples
• Feature Documentation - Generated feature-doc artifact format

---

Examples

Deep Learning Examples

Simple ships multiple deep learning examples across pure-Simple, model-training, and GPU-oriented flows:

Pure Simple Neural Networks:

# XOR neural network training
bin/simple examples/pure_nn/xor_training_example.spl

# Linear regression (learns y = 2x + 1)
bin/simple examples/pure_nn/simple_regression.spl

# Iris flower classification
bin/simple examples/pure_nn/iris_classification.spl

MedGemma Korean Fine-Tuning:

# Progressive LoRA training to prevent catastrophic forgetting
bin/simple examples/medgemma_korean/run_all.spl

CUDA Programming:

# Direct CUDA C API - multi-GPU, streams, events
bin/simple examples/cuda/basic.spl

See Deep Learning Guide for current documentation.

Other Examples

The examples/ directory contains additional working examples:

Example	Description
cli_demo.spl	Command-line argument parsing
file_async_basic.spl	Async file I/O operations
ui_todo_app.spl	Cross-platform UI application
vulkan_triangle.spl	GPU rendering with Vulkan
async_tcp_echo_server.spl	Async TCP networking

Run an example:

bin/simple examples/cli_demo.spl

---

SSpec Scenario Manuals

Feature and system documentation is generated from executable SSpec .spl scenarios. SPipe is the related runner/docgen process; SSpec is the authoring style: write readable step("...") actions, keep executable assertions in the same scenario, and let docgen render compact manual steps with folded source.

use std.spec.*

describe "Dashboard actions":
    # @inline
    it "operator has an authenticated session":
        step("Open the sign-in page")
        step("Submit valid credentials")

    it "operator reviews dashboard actions":
        # @include("operator has an authenticated session")
        step("Open the actions panel")
        expect("actions").to_equal("actions")

Generated manual:

1. Open the sign-in page
2. Submit valid credentials
3. Open the actions panel
   - Expected: "actions" equals `actions`

Given_*, When_*, and Then_* helper naming is legacy style. Use step("...") for new SSpec manuals. See the SSpec Scenario Manual Guide.

Generated docs land in the numbered documentation tree, primarily under doc/06_spec/, so the checked examples stay close to the current spec artifacts.

---

Grammar & Specification

Language Grammar

Simple’s current language references are split between the guide tree for user-facing explanations and the spec tree for executable or generated reference material.

Current Reference Documents:

• Syntax Quick Reference - Fast public-language reference
• Syntax Guide - User-facing language walkthrough
• Language Spec Index - Current generated spec index
• Syntax Spec - Spec artifact for syntax coverage
• Types Spec - Spec artifact for type-system coverage
• Modules Spec - Spec artifact for module-system coverage

Quick Grammar Reference:

# Top-level
program ::= statement*

# Statements
statement ::= function_def | class_def | struct_def | enum_def
            | import_stmt | export_stmt | expr_stmt

# Expressions (Pratt parser)
expr ::= literal | identifier | binary_op | unary_op
       | call | index | field_access | lambda
       | if_expr | match_expr | block

# Types
type ::= identifier | array_type | tuple_type | fn_type
       | optional_type | result_type | generic_type

# Literals
literal ::= integer | float | string | bool | array | dict | tuple

Specification Index

The current spec and guide material is organized under the numbered documentation tree:

Core Language:

• Syntax Spec - Syntax-oriented spec material
• Types Spec - Type-system spec material
• Data Structures Spec - Data-structure coverage
• Functions Spec - Functions and pattern matching
• Traits Spec - Traits and implementations
• Memory Spec - Ownership and borrowing
• Modules Spec - Import/export system

Advanced Features:

• Concurrency Spec - Async and concurrency behavior
• Metaprogramming Spec - Macros and decorators
• Macro Spec - Macro-specific executable coverage
• Capability Effects - Capability/effect system
• Standard Library Guide - Stdlib structure and usage
• SFFI Guide - Interop guidance
• External Native Libraries - Optional host-library integration

Testing & Tooling:

• Testing Guide - Test runner and matchers
• SSpec Scenario Manual Guide - Scenario manuals generated from executable specs
• Coverage Guide - Coverage and SDoctest enforcement
• Lint Guide - Lint rules and workflow
• MCP Guide - MCP workflow and registration

GPU & Platform:

• GPU Programming Guide - GPU usage
• Deep Learning Guide - Model-oriented examples
• Baremetal Guide - Platform and baremetal flows

See doc/README.md, doc/06_spec/README.md, and doc/07_guide/README.md for the current documentation entry points.

---

Project Structure

simple/
├── bin/                      # CLI entry points
│   ├── simple               # Main CLI (shell wrapper)
│   └── release/             # Pre-built release binaries
│       └── simple           # Pre-built runtime (33 MB)
│
├── src/                      # Simple source code (100% Simple)
│   ├── app/                  # Applications
│   │   ├── cli/             # Main CLI dispatcher
│   │   ├── build/           # Self-hosting build system
│   │   ├── mcp/             # MCP server (Model Context Protocol)
│   │   ├── lsp/             # Language server protocol
│   │   ├── io/              # SFFI wrappers (file, process, etc.)
│   │   └── ...              # 50+ tool modules
│   ├── lib/                  # Libraries
│   │   ├── database/        # Unified database (BugDB, TestDB, etc.)
│   │   └── pure/            # Pure Simple DL (tensor, autograd, nn)
│   ├── std/                  # Standard library
│   │   ├── src/             # Library source
│   │   └── test/            # Library tests
│   └── compiler/             # Compiler infrastructure
│       ├── backend/         # Code generation
│       ├── inference/       # Type inference
│       └── parser/          # Parser and treesitter
│
├── examples/                 # Example programs
│   ├── pure_nn/             # Deep learning examples
│   └── gpu/vulkan/          # GPU computing examples
│
├── test/                     # Test suites
│   ├── integration/         # Integration tests
│   ├── system/              # System tests
│   └── intensive/           # Intensive feature tests
│
├── doc/                      # Documentation
│   ├── spec/                # Language specifications
│   ├── guide/               # User guides
│   ├── design/              # Design documents
│   └── report/              # Session reports
│
└── src/verification/             # Lean 4 formal verification

---

Development

Building

# Debug build
simple build

# Release build
simple build --release

# With GPU support
simple build --release --features=vulkan

# Bootstrap build (minimal 9.3MB)
simple build --bootstrap

Testing

Full-suite snapshot (2026-02-14): 4,067/4,067 passing

Simple uses a broad test strategy spanning spec tests, SDoctest, coverage, and system lanes. The counts below are from the linked 2026-02-14 report:

# All tests (4,067 tests in 17.4 seconds)
simple test

# Run specific test file
simple test path/to/spec.spl

# With verbose output
simple test --verbose

# Coverage reports
simple build coverage

Test Coverage:

• Core interpreter: 227 tests
• Compiler: 306 tests
• Standard library: 428 tests
• Applications: 142 tests
• Libraries (ML, Physics, Game): 185 tests
• Integration & Coverage: 2,779 tests

Performance:

• Total execution: 17.4 seconds
• Average per test: 4.3ms
• All tests deterministic and fast

Performance Profiles:

• Language profile: scripts/check/check-cross-language-perf.shs generates doc/09_report/cross_language_perf_2026-06-06.md
• GUI profile: tools/gui_perf_bench/run_all_benchmarks.shs generates doc/09_report/gui_perf_benchmark_2026-06-06.md
• Startup/TUI profile: scripts/check/check-startup-size-performance-audit.shs records TUI startup rows in doc/09_report/startup_size_performance_audit_2026-05-27.md

See doc/09_report/session/full_test_suite_results_2026-02-14.md for detailed test analysis.

Code Quality

# Check before commit (fmt + lint + test)
simple build check

# Full check (includes coverage + duplication)
simple build check --full

# Format code
simple build fmt

# Lint
simple build lint

---

AI Tooling (MCP, LSP, Plugin)

Simple ships with MCP servers, LSP servers, and Claude Code plugins — all written in Simple.

Install Simple MCP Server

The Simple MCP server exposes repo-native tools for code diagnostics, VCS, build, test, debug, and related workflows. For current registration details, use the repo scripts and guide docs rather than relying on hardcoded counts here.

# From a repo checkout — register with Claude Code
claude mcp add simple-mcp -- \
  /absolute/path/to/simple/bin/simple \
  /absolute/path/to/simple/src/app/mcp/main.spl

# Or use the project .mcp.json (auto-detected by Claude Code)
sh config/mcp/install.shs

Install Simple MCP Plugin

The simple-mcp Claude plugin is a repo-checkout plugin. Install it from a Simple repository checkout; it is not a standalone portable runtime bundle.

claude plugin marketplace add tools/claude-plugin/marketplace
claude plugin install simple-mcp@simple-local

The plugin launches bin/simple_mcp_server from the repository root.

Install Simple LSP Plugin

The Simple language server provides completions, hover, go-to-definition, diagnostics, and semantic tokens for .spl / .shs files.

# From a repo checkout
claude plugin marketplace add tools/claude-plugin/marketplace
claude plugin install simple-lsp@simple-local

Binary full path: bin/simple run src/app/lsp/main.spl

Install Both (Quick Setup)

cd /path/to/simple

# 1. MCP server
sh config/mcp/install.shs

# 2. LSP plugin
claude plugin marketplace add tools/claude-plugin/marketplace
claude plugin install simple-lsp@simple-local

Prompt Examples

Once the MCP server and LSP plugin are installed, try these prompts in Claude Code:

> "Run the linter on src/app/cli/main.spl and fix any warnings"

> "Show me all unused variables in the compiler frontend"

> "Run the unit tests for the SDN parser"

> "Build the project in release mode and show the result"

> "What does the function `parse_expression` in the parser do?"

> "Find all TODO items in the codebase"

> "Check the doc coverage for the standard library"

> "Debug why test/01_unit/lib/common/value_spec.spl is failing"

---

Editor Plugins

VSCode Extension

Full-featured extension with Tree-sitter highlighting, LSP integration, and math block support.

cd src/app/vscode_extension
npm install && npm run compile && npm run package
code --install-extension simple-language-0.1.0.vsix

Key features:

• Semantic syntax highlighting (Tree-sitter powered)
• LSP: completions, hover, go-to-definition, diagnostics
• Math block highlighting for m{}, loss{}, nograd{} with nested brace support
• Test CodeLens: "Run Test/File/Doctest" gutter arrows on describe/it/context/sdoctest blocks
• AI-powered completions and chat (requires GitHub Copilot)

See src/app/vscode_extension/README.md for full documentation.

Neovim Plugin

-- lazy.nvim
{ "nicholasgasior/simple.nvim", ft = "simple", opts = {} }

-- Or from project checkout
vim.opt.rtp:prepend("/path/to/simple/src/app/nvim_plugin")
require("simple").setup()

Key features:

• LSP integration with auto-detection
• Math block conceal with inline Unicode preview (frac(1,2) -> (1)/(2), alpha -> α, sqrt(x) -> √(x))
• Test lens: "Run" virtual text beside test blocks
• Tree-sitter queries (highlights, folds, text objects, injections)
• Brief view (fold to signatures)

See src/app/nvim_plugin/README.md for full documentation.

---

TRACE32 Tools

MCP servers, CMM language server, and CLI tools for Lauterbach TRACE32 debuggers. See examples/10_tooling/trace32_tools/README.md for full documentation.

The repo-managed container flow is headless and uses t32mciserver. It does not ship bundled TRACE32 GUI compatibility libraries; vendor runtime files must come from your local /opt/t32 installation.

Primary lifecycle wrapper:

scripts/t32q.shs build
scripts/t32q.shs on
scripts/t32q.shs wait
scripts/t32q.shs ping
scripts/t32q.shs reopen
scripts/t32q.shs off

GUI container reopen path:

scripts/t32q.shs gui-on
scripts/t32q.shs gui-reopen
scripts/t32q.shs off

gui-on uses the Docker/Podman TRACE32 GUI path with host X11 forwarding, so it requires a real host X11 session (DISPLAY, /tmp/.X11-unix, and usually XAUTHORITY). For quick diagnostics use:

scripts/t32q.shs doctor

Hello-world firmware smoke:

scripts/t32_semihost_hello.shs --board stm32wb
scripts/t32_semihost_hello.shs --board stm32h7
scripts/t32_semihost_hello.shs --board stm32wb --build-only

Optional: Install T32 MCP Servers

These TRACE32 MCP servers are not installed by the default project MCP setup. Register them manually only if you actively use TRACE32 tooling.

cd /path/to/simple

# T32 MCP — controls live TRACE32 debug sessions (23 tools)
claude mcp add t32-mcp -- \
  /absolute/path/to/simple/bin/simple \
  /absolute/path/to/simple/examples/10_tooling/trace32_tools/t32_mcp/main.spl

# T32 LSP MCP — CMM script analysis, no hardware needed (6 tools)
claude mcp add t32-lsp-mcp -- \
  /absolute/path/to/simple/bin/simple \
  /absolute/path/to/simple/examples/10_tooling/trace32_tools/t32_lsp_mcp/main.spl

Binary full paths:

• T32 MCP: bin/simple run examples/10_tooling/trace32_tools/t32_mcp/main.spl
• T32 LSP MCP: bin/simple run examples/10_tooling/trace32_tools/t32_lsp_mcp/main.spl

Install CMM LSP Plugin

claude plugin marketplace add tools/claude-plugin/marketplace
claude plugin install cmm-lsp@simple-local

Binary full path: bin/simple run examples/10_tooling/trace32_tools/cmm_lsp/mod.spl --lsp

T32 Prompt Examples

> "Parse this CMM script and check for errors: config/t32/stm32h7_gdb_start.cmm"

> "Connect to TRACE32 on localhost:20000 and read the CPU registers"

> "Show me all labels and macros defined in my CMM script"

> "Convert this GUI PRACTICE script to CLI batch mode"

> "Check if my CMM script has any undefined macros or unreachable code"

> "Set a breakpoint at main, run to it, and show local variables"

> "What TRACE32 commands are available for memory access?"

> "Auto-complete suggestions for 'Data.LOAD' in my CMM script"

---

Contributing

See CLAUDE.md for development guidelines and AGENTS.md for AI agent instructions.

Documentation Structure:

• Specifications go in doc/06_spec/ (what the language supports)
• Guides go in doc/07_guide/ (how to use features)
• Research goes in doc/01_research/ (why/how decisions were made)
• Plans go in doc/03_plan/ (implementation roadmaps)
• Reports go in doc/09_report/ (session summaries and completion reports)

---

License

Apache License 2.0. See LICENSE.

Bundled third-party runtime components and redistribution notices are listed in THIRD_PARTY_NOTICES.md.

Release packages also include THIRD_PARTY_NOTICES.md.

---

Resources

Official Documentation:

• Documentation Hub - Entry point for the numbered docs tree
• Language Specification - Current spec index
• User Guides - Practical tutorials

Quick References:

• Syntax Quick Reference
• Type System Guide
• GPU Computing Guide

Development:

• Architecture Overview
• Feature Documentation
• Implementation Plans