On Thu, Oct 6, 2016 at 12:13 AM, Gregory Ewing
<greg.ew...@canterbury.ac.nz> wrote:
> Chris Angelico wrote:
>>
>> How do you handle variadic functions?
>
>
> All functions in Haskell take exactly one argument, so
> there isn't really any such thing as a variadic function.
> The argument can be a list, however, so you can get the
> same effect.
That basically just means you always pack and unpack *args. If you're
talking about currying a function - particularly *automatic* currying
- functions have to take multiple arguments, and in a naive
implementation, a fixed number. Something like:
def auto_curry(f):
@functools.wraps(f)
def curry_or_run(*args):
if len(args) >= f.__code__.co_argcount:
return f(*args)
return functools.partial(curry_or_run, *args)
return curry_or_run
@auto_curry
def f(a, b, c):
return a + b * c
print(f(1)(2, 3))
print(f(1, 2)(3))
print(f(1, 2, 3))
print(f(1)(2)(3))
That works fine as long as you can probe the function for co_argcount.
(And as long as you don't have keyword arguments, but they're a bit of
a Python peculiarity so I doubt that'll get in the way.) Hence my
query about how variadic functions and automatic currying work - how
does it know whether to curry or run?
ChrisA
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