Code Runner Skill

This skill enables you to run code snippets in multiple programming languages directly from the command line.

When to Use This Skill

Use this skill when:

• The user wants to run or execute a code snippet
• Testing algorithm implementations or logic
• Verifying expected output of code
• Running quick scripts or one-liners
• Checking syntax or runtime behavior
• Demonstrating code functionality

Supported Languages

The following languages are supported (requires the interpreter/compiler to be installed):

| Language | Command | File Extension |

|----------|---------|----------------|

| JavaScript | node | .js |

| TypeScript | ts-node | .ts |

| Python | python | .py |

| Java | java (compile & run) | .java |

| C | gcc (compile & run) | .c |

| C++ | g++ (compile & run) | .cpp |

| Go | go run | .go |

| Rust | rustc (compile & run) | .rs |

| Ruby | ruby | .rb |

| PHP | php | .php |

| Perl | perl | .pl |

| Lua | lua | .lua |

| R | Rscript | .r |

| Swift | swift | .swift |

| Kotlin | kotlin | .kts |

| Scala | scala | .scala |

| Groovy | groovy | .groovy |

| Dart | dart | .dart |

| Julia | julia | .jl |

| Haskell | runhaskell | .hs |

| Clojure | clojure | .clj |

| F# | dotnet fsi | .fsx |

| C# | dotnet script | .csx |

| PowerShell | pwsh | .ps1 |

| Bash | bash | .sh |

| Batch | cmd /c | .bat |

| CoffeeScript | coffee | .coffee |

| Crystal | crystal | .cr |

| Elixir | elixir | .exs |

| Nim | nim compile --run | .nim |

| OCaml | ocaml | .ml |

| Racket | racket | .rkt |

| Scheme | scheme | .scm |

| Lisp | sbcl --script | .lisp |

See references/LANGUAGES.md for detailed language configuration.

How to Run Code

Step 1: Identify the Language

Determine the programming language from:

• User's explicit request (e.g., "run this Python code")
• File extension if provided
• Code syntax patterns

Step 2: Execute Using the Runner Script

⚠️ Important for AI Agents: Use stdin to avoid escaping issues with quotes, backslashes, and special characters.

Recommended Method (stdin):

echo "<code>" | node scripts/run-code.cjs <languageId>

Alternative Method (CLI argument - for simple code only):

node scripts/run-code.cjs <languageId> "<code>"

Example - JavaScript:

echo "console.log('Hello, World!')" | node scripts/run-code.cjs javascript

Example - Python:

echo "print('Hello, World!')" | node scripts/run-code.cjs python

Example - Java (multi-line):

echo "public class Test {
    public static void main(String[] args) {
        System.out.println(\"Hello from Java!\");
    }
}" | node scripts/run-code.cjs java

Example - Multi-line code from variable:

# In bash
CODE='import math
print("Pi:", math.pi)
print("Result:", math.factorial(5))'
echo "$CODE" | node scripts/run-code.cjs python

# In PowerShell (inline here-string)
@"
import math
print("Pi:", math.pi)
print("Result:", math.factorial(5))
"@ | node scripts/run-code.cjs python

Step 3: Return Results

• Show the output (stdout) to the user
• If there are errors (stderr), explain what went wrong
• Suggest fixes for common errors

Platform Notes

Windows

• Use cmd /c for batch scripts
• PowerShell scripts require pwsh or powershell
• Path separators use backslash \

macOS / Linux

• Bash scripts work natively
• Swift available on macOS
• Use #!/usr/bin/env shebang for portable scripts

Error Handling

Common issues and solutions:

1. Command not found: The language interpreter is not installed or not in PATH
• Suggest installing the required runtime
• Provide installation instructions

1. Syntax errors: Code has syntax issues
• Show the error message
• Point to the line number if available

1. Runtime errors: Code runs but fails during execution
• Display the stack trace
• Explain the error type

1. Timeout: Code takes too long (default: 30 seconds)
• Warn about infinite loops
• Suggest optimizations

Security Considerations

⚠️ Important: Running arbitrary code can be dangerous. Always:

1. Review the code before execution
2. Be cautious with code that:
• Accesses the file system
• Makes network requests
• Executes system commands
• Modifies environment variables
3. Consider running in a sandboxed environment for untrusted code

Examples

Example 1: Run a JavaScript calculation

echo "console.log(Array.from({length: 10}, (_, i) => i * i))" | node scripts/run-code.cjs javascript

Output: [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

Example 2: Run Python with imports

echo "import math; print(math.factorial(10))" | node scripts/run-code.cjs python

Output: 3628800

Example 3: Test a Go function

echo 'package main; import "fmt"; func main() { fmt.Println("Hello from Go!") }' | node scripts/run-code.cjs go

Output: Hello from Go!