listhell.md

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Table of Contents

• Listhell: It's not Lisp, it's not Python, it's not Haskell
  • Features
  • What Listhell is
  • Comboability
  • Notes
  • CAUTION
  • Etymology?

Listhell: It's not Lisp, it's not Python, it's not Haskell

Python with prefix syntax for function calls, and automatic currying.

Powered by mcpyrate and unpythonic.

from unpythonic.dialects import dialects, Listhell  # noqa: F401

from unpythonic import foldr, cons, nil, ll

(print, "hello from Listhell")

double = lambda x: 2 * x
my_map = lambda f: (foldr, (compose, cons, f), nil)
assert (my_map, double, (q, 1, 2, 3)) == (ll, 2, 4, 6)

Features

In terms of unpythonic.syntax, we implicitly enable prefix and autocurry for the whole module.

The following are dialect builtins:

• apply, aliased to unpythonic.fun.apply
• compose, aliased to unpythonic's currying right-compose composerc
• q, u, kw for the prefix syntax (note these are not mcpyrate's q and u, but those from unpythonic.syntax, specifically for prefix)

For detailed documentation of the language features, see unpythonic.syntax.

If you need more stuff, unpythonic is effectively the standard library of Listhell, on top of what Python itself already provides.

What Listhell is

Listhell is a dialect of Python implemented via macros and a thin whole-module AST transformation. The dialect definition lives in unpythonic.dialects.listhell. Usage examples can be found in the unit tests.

Listhell is essentially a demonstration of how Python could look, if it had Lisp's prefix syntax for function calls and Haskell's automatic currying.

It's also a minimal example of how to make an AST-transforming dialect.

Comboability

Only outside-in macros that should expand after autocurry (currently, unpythonic provides no such macros) and inside-out macros that should expand before autocurry (there are two, namely tco and continuations) can be used in programs written in the Listhell dialect.

Notes

If you like the idea and want autocurry for a Lisp, try spicy for Racket.

CAUTION

Not intended for serious use.

Etymology?

Prefix syntax of Lisp, speed of Python, and readability of Haskell, all in one.