[issue13430] Add a curry function to the functools module

[Marko Nervo]

Marko Nervo <marko at python.it> added the comment:

> But so does functools.partial. So the question is, what use case does it
> help that functools.partial doesn't?

Sure, it's common `defining new functions on other functions`... more times. Here a stupid example with fold (our reduce).


@curry
def fold(function, start, sequence):
    if len(sequence) == 0:
        return start
    else:
        return fold(function, function(start, sequence[0]), sequence[1:])


Now, someone could be define a generic summer function by fold.


import operator as op

summer = fold(op.add)


Now, an other programmer could be use summer for defining listsummer (a function which sum only list), as follow.


listsummer = summer([])


In addition, curry is cleaver than functools.partial. 


summer = functools.partial(fold, op.add)
listsummer = functools.partial(summer, [])


However, it is an additional feature. Nobody forces you to use it, but if you need it... Yeah, you could rewrite it each time, but why? It is perfect in functools (:

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<http://bugs.python.org/issue13430>
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