ThreadHeadThreadTail.py

# A quick proof-of-concept. There is some room for improvement.
# Note also that Clojure's macros have no loss of performance compared to writing their expansion (i.e. nested calls) in the first place.
# This, on the other hand, creates a new object per nesting. Python is very flexible, but it's not fast.

class Thead:
    """
    Thread-Head class. Like Clojure's -> (thread-first) macro.
    >>> import operator as op
    >>> Thead(5)(op.sub, 3)(op.mul, 10).result
    20
    >>> Thead('XY')(op.add, 'a')(op.mul, 2)(op.add, 'b').result
    'XYaXYab'
    """
    # see also, Drython's DoTo. Method calls could also be threaded in Thead using __getattribute__ 
    def __init__(self, result):
        self.result = result
    def __call__(self, func, *args, **kwargs):
        return Thead(func(self.result, *args, **kwargs))

class Thail:
    """
    Thread-Tail class. Like Clojure's ->> (thread-last) macro.
    >>> import operator as op
    >>> Thail(5)(op.sub, 3)(op.mul, 10).result
    -20
    >>> Thail('XY')(op.add, 'a')(op.mul, 2)(op.add, 'b').result
    'baXYaXY'
    """
    def __init__(self, result):
        self.result = result
    def __call__(self, func, *args, **kwargs):
        return Thail(func(*args, self.result, **kwargs))

import doctest
doctest.testmod()

should the Thread-Tail class be called TTail?

Maybe they should just be Thead and Thail, since I intended it to be a Portmanteau of "Thread-head" and "Thread-tail". The words need to be short and easy to type, since Clojure's -> and ->> are even shorter.