Rewrite OCaml implementation in Rust

[Copilot]

Ports the Hindley-Milner type inference interpreter from OCaml to Rust.

Implementation

• AST (src/ast.rs): Expression types with unary/binary ops, closures, let-bindings, conditionals
• Lexer (src/lexer.rs): Character-based tokenizer with operator precedence tokens
• Parser (src/parser.rs): Recursive descent parser handling operator precedence and closure syntax
• Type Checker (src/type_check.rs): Algorithm W with:
  • Unification with occurs check for infinite type prevention
  • Substitution composition for constraint threading
  • Let-polymorphism via generalization/instantiation
• Evaluator (src/eval.rs): Call-by-value semantics with substitution-based closures
• CLI (src/main.rs): REPL and single-expression evaluation modes

Type Inference Example

// Polymorphic identity function
let id = x -> x in id
// Type: ($1 -> $1)

// Self-application via let-polymorphism
let id = x -> x in id id
// Type: ($1 -> $1)

// Higher-order function inference
let twice = f -> x -> f (f x) in twice
// Type: (($1 -> $1) -> ($1 -> $1))

CI/CD

Added .github/workflows/rust.yml with automated checks:

• test: Build and run all 16 tests with dependency caching
• fmt: Verify code formatting with cargo fmt
• clippy: Run linter with all warnings as errors (-D warnings)

Notes

• Thread-safe test execution via mutex (global gensym counter)
• Deterministic variable ordering in lower() for consistent test results
• Original OCaml implementation preserved in /lib and /bin
• All code passes formatting and linting checks

Original prompt

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This section details on the original issue you should resolve

<issue_title>Rewrite in rust</issue_title>
<issue_description>Please rewite in rust to increase blazingly fast</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Rewrite in rust #1

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[Ashwagandhae]

@copilot make the github actions work. also make it work in web aseembly so it can run in browser.

[AvaWandersleben]

@copilot rewrite all of the code in completely Go

this is so slow and bad

[nyiyui]

@copilot Run Rust tests in CI

[AvaWandersleben]

@copilot @copilot @copilot @copilot @copilot @copilot @copilot @copilot @copilot @copilot @copilot

[Copilot]

@copilot Run Rust tests in CI

Added .github/workflows/rust.yml with CI jobs for tests, formatting (cargo fmt), and linting (cargo clippy). All checks pass successfully. (4f81b9d)