What is ailang-debug?

This Claude skill is a specialized debugging assistant for the AILANG programming language, designed to identify and resolve type errors, parse failures, and runtime issues. It provides developers with actionable solutions for common functional programming hurdles, such as managing strict typing, handling missing semicolons, and transitioning from imperative loops to recursive patterns.

When should I use ailang-debug?

ailang-debug is useful in the following scenarios: • Fixing 'undefined variable' errors by identifying missing standard library imports or correcting built-in function names. • Resolving type mismatch errors, such as using the 'show' function to convert integers or other types into strings for printing. • Refactoring prohibited imperative structures like 'for' or 'while' loops into valid AILANG recursive functions and match expressions. • Troubleshooting syntax errors related to AILANG's specific requirements, such as mandatory semicolons between statements in code blocks. • Optimizing development workflows by utilizing AILANG CLI tools for type-checking and exploring built-in module documentation.

name	AILANG Debug
description	Debug AILANG code errors. Use when you encounter type errors, parse errors, or runtime failures in AILANG programs.

AILANG Debug

Fix common AILANG errors quickly.

Quick Reference

Error	Cause	Fix
`undefined variable: print`	Not in entry module	Use entry module or `import std/io (print)`
`undefined variable: println`	Wrong function name	Use `print` not `println`
`undefined variable: map`	Not imported	`import std/list (map)` or write recursive
`No instance for Num[string]`	`print(42)`	Use `print(show(42))`
`expected }, got let`	Missing semicolon	Add `;` between statements
`unexpected token: for`	No loops in AILANG	Use recursion instead
`unexpected token: in`	No `for x in xs`	Use `match xs { ... }`

Decision Tree

Error message?
│
├─ "undefined variable: X"
│   └─ Is X a builtin?
│       ├─ Yes → Import it: ailang builtins list | grep X
│       └─ No → Check spelling, define it
│
├─ "expected }, got ..."
│   └─ Missing semicolon between statements
│       Fix: let x = 1; let y = 2; x + y
│
├─ "No instance for Num[string]"
│   └─ Passing number to string function
│       Fix: print(show(42)) not print(42)
│
├─ "unexpected token: for/while/in"
│   └─ AILANG has no loops!
│       Fix: Use recursion with match
│
└─ Parse error with braces
    └─ Unmatched { } or missing expression
        Fix: Check all blocks are closed

Common Fixes

1. Missing Semicolons

-- WRONG
export func main() -> () ! {IO} {
  let x = 10
  let y = 20
  print(show(x + y))
}

-- CORRECT (semicolons between statements)
export func main() -> () ! {IO} {
  let x = 10;
  let y = 20;
  print(show(x + y))
}

2. Print Needs String

-- WRONG: print expects string
print(42)

-- CORRECT: convert with show()
print(show(42))

3. No Loops - Use Recursion

-- WRONG: no for loops
for i in range(5) { print(show(i)) }

-- CORRECT: recursive function
export func printRange(n: int) -> () ! {IO} {
  if n <= 0 then () else {
    print(show(n));
    printRange(n - 1)
  }
}

4. Import Standard Library

-- WRONG: map not in scope
let doubled = map(\x. x * 2, nums)

-- CORRECT: import from std/list
import std/list (map)
let doubled = map(\x. x * 2, nums)

-- OR: write it yourself (recursion)
export func myMap[a,b](f: func(a) -> b, xs: [a]) -> [b] {
  match xs {
    [] => [],
    hd :: tl => f(hd) :: myMap(f, tl)
  }
}

Debugging Workflow

Type-check first (faster feedback):
```
ailang check file.ail
```
Read error location - line:column tells you where
Check the pattern above for your error type

Use REPL for quick tests:

ailang repl
> show(42)
> 1 + 2
> :type \x. x * 2

List builtins to find imports (CLI is source of truth):

# SOURCE OF TRUTH: Full documentation with examples
ailang builtins list --verbose --by-module

# Search for specific function with full docs
ailang builtins list --verbose | grep -A 10 "map"

# See a specific module's functions
ailang builtins list --verbose --by-module | grep -A 30 "std/list"

Resources

Always prefer CLI commands (ailang prompt, ailang builtins list --verbose) over static docs - they're always up-to-date.

See resources/error_catalog.md for additional error patterns.

ailang-debug

When & Why to Use This Skill

Use Cases