FEATURE_AUDIT.md

Compilets Feature Audit

Date: January 2026 Version: Current development state Test Status: 62/62 tests passing

Overview

Compilets is a native TypeScript compiler that compiles TypeScript to native executables using SWC (parsing) and LLVM (code generation).

Run ./run_tests.sh to execute the full test suite.

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Working Features ✅

Core Language

Feature	Status	Notes
Numbers (f64)	✅ Full	All arithmetic (+, -, *, /, %) work
Booleans	✅ Full	true/false, comparison, logical operators
Strings	✅ Partial	Literals, concatenation, length, indexOf work
Variables	✅ Full	let/const declarations
Unary operators	✅ Full	Negation (-x), logical not (!x)
Ternary operator	✅ Full	condition ? a : b

Control Flow

Feature	Status	Notes
If/else	✅ Full	All branching patterns
While loops	✅ Full	Including break/continue
For loops	✅ Full	Including break/continue
Break	✅ Full	Works in all loops
Continue	✅ Full	Works in all loops

Functions

Feature	Status	Notes
Function declaration	✅ Full	Named functions
Function calls	✅ Full	Direct calls
Recursion	✅ Full	Self-referential calls
Parameters	✅ Full	Multiple parameters
Return values	✅ Full	Explicit returns

Classes

Feature	Status	Notes
Class declaration	✅ Full	Basic class syntax
Constructors	✅ Full	With parameters
Instance fields	✅ Full	this.field access
Instance methods	✅ Full	Method calls on instances
Class inheritance	✅ Full	extends keyword
super() calls	✅ Full	Parent constructor calls

Arrays

Feature	Status	Notes
Array literals	✅ Full	[1, 2, 3] syntax
Array indexing	✅ Full	arr[i] read/write
Array length	✅ Full	arr.length property

Other

Feature	Status	Notes
Enums	✅ Full	Numeric and string enums
BigInt	✅ Full	256-bit integers
Simple closures	✅ Partial	Arrow functions work locally
console.log	✅ Full	Numbers and strings
setTimeout	✅ Full	Async timer support

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Not Working / Missing ❌

Operators

Feature	Status	Priority	Notes
++/-- operators	✅ Full	-	Pre/post increment/decrement work
Compound assignment	✅ Full	-	+=, -=, *=, /=, %=, **=, &=,
Bitwise operators	✅ Full	-	&,
** (exponent)	✅ Full	-	2 ** 3 = 8, also **= compound assignment

Strings

Feature	Status	Priority	Notes
string.slice()	✅ Full	-	Returns substring from start to end index
string.substring()	✅ Full	-	Works (similar to slice but swaps args if start > end)
string.split()	✅ Full	-	Split by delimiter, returns string[]
string.trim()	✅ Full	-	Remove whitespace from both ends
string.toLowerCase()	✅ Full	-	Convert to lowercase
string.toUpperCase()	✅ Full	-	Convert to uppercase
Template literals	✅ Full	-	Backtick strings with ${expr} interpolation

Arrays

Feature	Status	Priority	Notes
push/pop	✅ Full	-	Array mutation methods
shift/unshift	✅ Full	-	Array mutation methods
indexOf/includes	✅ Full	-	Search methods
map/filter/reduce	✅ Full	-	Functional array methods
forEach	✅ Full	-	Iteration method
slice	✅ Full	-	Array slicing (slice(start, end?))
splice	✅ Full	-	Array splice (splice(start, deleteCount?, ...items))
Mixed-type arrays	✅ Full	-	Arrays can hold mixed types (string|number)[] using NaN-boxing

Classes

Feature	Status	Priority	Notes
Method inheritance	✅ Full	-	Methods inherited and can be overridden
Static methods	✅ Full	-	Class-level methods
Static fields	✅ Full	-	Class-level properties
Getters/setters	✅ Full	-	get/set accessors work
Private fields (#)	✅ Full	-	ES2022 private class fields (#field)

Functions/Closures

Feature	Status	Priority	Notes
Closures as args	✅ Full	-	Arrow functions work as callback arguments
Higher-order functions	✅ Full	-	Named functions and closures work as callbacks
Returning closures	✅ Full	-	Mutable captures work when returned; use type inference for closure return types
Rest parameters	✅ Full	-	...args syntax collects remaining arguments into array
Default parameters	✅ Full	-	Parameters with default values

Control Flow

Feature	Status	Priority	Notes
Try-catch-finally	✅ Full	-	Works with throw, catch, finally
Switch statement	✅ Full	-	With fallthrough support
For-of loops	✅ Full	-	Array iteration
For-in loops	✅ Full	-	Object key iteration

Type System

Feature	Status	Priority	Notes
Type extraction	✅ Full	-	Types extracted from annotations
Generics	✅ Full	-	Monomorphization generates specialized functions/classes
Interfaces	✅ Full	-	Interface declarations with properties and methods
Type aliases	✅ Full	-	type X = ... declarations
Constraint checking	✅ Full	-	T extends Foo constraints validated
Type guards	✅ Full	-	typeof operator and type narrowing with union types
Union types	✅ Full	-	Variables with string

Modules

Feature	Status	Priority	Notes
import/export	✅ Full	-	Named imports/exports, re-exports work
require()	✅ Full	-	CommonJS require() for built-in modules (fs, path, crypto)

Standard Library

Feature	Status	Priority	Notes
fs module	✅ Full	-	readFileSync, writeFileSync, existsSync, mkdirSync, unlinkSync
path module	✅ Full	-	join, dirname, basename, extname, resolve
process.env	✅ Full	-	Environment variables (process.env.VARNAME)
crypto	✅ Full	-	randomBytes, randomUUID, sha256, md5
Date	✅ Full	-	Date.now(), new Date(), getTime(), toISOString(), component getters
JSON	✅ Full	-	JSON.parse and JSON.stringify
Math	✅ Full	-	floor, ceil, round, abs, sqrt, pow, min, max, random
Map/Set	✅ Full	-	Map and Set collection types
RegExp	✅ Full	-	string.replace(), regex.test(), string.match() (global and non-global)

Other

Feature	Status	Priority	Notes
Destructuring	✅ Full	-	Array and object destructuring (shorthand, rename, defaults, rest), including nested and rest patterns
Spread operator	✅ Full	-	[...arr, x] array spread syntax
Optional chaining	✅ Full	-	obj?.prop, obj?.[index]
Nullish coalescing	✅ Full	-	?? operator
Method chaining	✅ Full	-	Array/string method chains (e.g. arr.filter().map(), str.toLowerCase())
Utility types	✅ Full	-	Partial, Pick, Record, Omit, ReturnType, Readonly erased at compile time
Decorators	⚠️ Partial	-	@log method decorator (compile-time transformation)

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Test Files

The following test files are available in test-files/:

File	Tests
test_for.ts	For loops
test_for_in.ts	For-in loops (object key iteration)
test_break_continue.ts	Break and continue
test_enum.ts	Enum support
test_inheritance.ts	Class inheritance
test_simple_class.ts	Basic classes
test_closure_complex.ts	Closure support
test_timer.ts	setTimeout/async
test_mutable_capture.ts	Mutable closure captures
test_returning_closures.ts	Returning closures from functions
test_process_env.ts	process.env access
test_fs.ts	fs module (read/write/exists/mkdir/unlink)
test_path.ts	path module (join/dirname/basename/extname/resolve)
test_array_methods.ts	Array methods (push/pop/shift/unshift/indexOf/includes)
test_string_methods.ts	String methods (trim/toLowerCase/toUpperCase)
test_json.ts	JSON.parse and JSON.stringify
test_math.ts	Math functions (floor, ceil, round, abs, sqrt, pow, min, max, random)
test_crypto.ts	Crypto functions (randomBytes, randomUUID, sha256, md5)
test_date.ts	Date functions (Date.now, new Date, getTime, toISOString, getFullYear, etc.)
test_bitwise.ts	Bitwise operators (&,
test_regex.ts	RegExp support (test(), string.match(), string.replace())
test_object_destructuring.ts	Object destructuring (shorthand, rename, defaults, rest)
test_method_chaining.ts	Method chaining (arr.filter().map(), string chains)
test_utility_types.ts	TypeScript utility type erasure (Partial, Pick, Record, Omit, etc.)
test_rest_params.ts	Rest parameters (...args syntax)
test_getters_setters.ts	Class getters and setters
test_private_fields.ts	Private class fields (#field syntax)
test_union_types.ts	Union types (string | number variables)
test_type_guards.ts	Type guards (typeof operator, type narrowing)
test_mixed_arrays.ts	Mixed-type arrays ((string|number)[])
test_require.ts	CommonJS require() for built-in modules
test_decorators.ts	Method decorators (@log)
test_integration_app.ts	Integration: classes, decorators, file I/O, arrays
test_data_pipeline.ts	Integration: generics, Map/Set, array methods, Math
test_cli_simulation.ts	Integration: fs, path, strings, try-catch, JSON

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Recommended Implementation Order

Phase 1: Core Language Completeness

1. ++/-- operators - ✅ DONE
2. Compound assignment (+=, etc) - ✅ DONE
3. Method inheritance - ✅ DONE

Phase 2: Error Handling & Modules

4. Try-catch-finally - ✅ DONE (already implemented!)
5. Module imports - ✅ DONE (already implemented!)

Phase 3: Standard Library

6. process.env - ✅ DONE
7. fs module - ✅ DONE
8. path module - ✅ DONE

Phase 4: Advanced Features

9. Generics - ✅ DONE (monomorphization, interfaces, type aliases, constraints)
10. Array methods - ✅ DONE (push, pop, shift, unshift, indexOf, includes)

Phase 5: Functional Programming

11. Higher-order functions - ✅ DONE (closures and named functions as callbacks)
12. Array HOF methods - ✅ DONE (map, filter, reduce, forEach)

Phase 6: Modern Syntax

13. Switch statements - ✅ DONE (with fallthrough support)
14. For-of loops - ✅ DONE (array iteration)
15. Destructuring - ✅ DONE (array destructuring with nested and rest patterns)
16. Spread operator - ✅ DONE (...array syntax)
17. Template literals - ✅ DONE (backtick strings with ${expr})
18. Default parameters - ✅ DONE (function parameters with defaults)
19. Optional chaining - ✅ DONE (obj?.prop, obj?.[index])
20. Nullish coalescing - ✅ DONE (?? operator)

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Runtime Notes

• No garbage collection - Memory leaks in long-running code
• Arrays are f64-only - No mixed-type arrays
• Dynamic array growth - Arrays grow automatically via push/unshift
• Async via event loop - setTimeout works with await