How to write a Python function for MARPLE¶

Every function called through ⌶ must follow this contract:

Accept one APLArray argument (monadic) or two (dyadic, left then right)
Return an APLArray

Monadic example¶

from marple.arraymodel import APLArray

def double(right: APLArray) -> APLArray:
    data = [x * 2 for x in right.data]
    return APLArray(list(right.shape), data)

Save this as mymodule.py somewhere on your Python path, then call it:

      (⌶'mymodule.double') 1 2 3
2 4 6

Dyadic example¶

from marple.arraymodel import APLArray, S

def power(left: APLArray, right: APLArray) -> APLArray:
    base = left.data[0]
    exp = right.data[0]
    return S(base ** exp)

      2 (⌶'mymodule.power') 10
1024

Error handling¶

If your function raises an exception, MARPLE wraps it in a DOMAIN ERROR. Return meaningful error messages in your exceptions to help users debug.