How to wrap a Python library for MARPLE

To use any Python library from MARPLE, write thin wrapper functions that translate between APLArray and native Python types.

Example: wrapping Python's math library

Create a file mathwrap.py:

import math
from marple.arraymodel import APLArray, S

def sqrt(right: APLArray) -> APLArray:
    """Monadic: square root of each element."""
    data = [math.sqrt(x) for x in right.data]
    return APLArray(list(right.shape), data)

def atan2(left: APLArray, right: APLArray) -> APLArray:
    """Dyadic: atan2(y, x) element-wise."""
    results = [math.atan2(y, x) for y, x in zip(left.data, right.data)]
    return APLArray(list(left.shape), results)

Use from MARPLE:

      sqrt ← ⌶'mathwrap.sqrt'
      sqrt 4 9 16
2 3 4

Steps

1. Write Python wrapper functions that accept/return APLArray
2. Place the module somewhere importable (on PYTHONPATH or installed as a package)
3. Call from APL via ⌶'module.function'

Tips

• Keep wrappers thin -- just convert types and delegate
• Use APLArray(list(right.shape), data) to preserve the input shape
• Use S(value) to return a scalar
• Raise clear exceptions for invalid inputs -- they become DOMAIN ERRORs

See also: Write a Python function, Using I-Beam