How to use I-Beam¶

The ⌶ operator calls Python functions from APL. Its operand is a string naming a Python callable using dotted module path notation:

      (⌶'marple.stdlib.io_impl.nread') '/tmp/data.txt'

Assign to a name for reuse¶

      readfile ← ⌶'marple.stdlib.io_impl.nread'
      readfile '/tmp/data.txt'

The derived function is first-class -- you can assign it, pass it to operators, and call it monadically or dyadically.

Dyadic usage¶

If the Python function accepts two APLArray arguments:

      'hello' (⌶'mymodule.myfunc') 'world'

Security¶

If the MARPLE_IBEAM_ALLOW environment variable is set, only module paths matching one of its comma-separated prefixes are permitted. Paths not on the allowlist raise a SECURITY ERROR.

MARPLE_IBEAM_ALLOW=marple.stdlib,myproject marple