[Python-ideas] Syntax for curried functions

[Steven D'Aprano]

Weeble wrote:
> Would this be crazy? Make this:
> 
> def spam(a,b,c)(d,e,f):
>     [BODY]
> 
> a synonym for:
> 
> def spam(a,b,c):
>     def spam2(d,e,f):
>         [BODY]
>     return spam2
> 
> As far as I can tell, it would always be illegal syntax right now, so
> it seems a safe change. And it would make it cleaner to write higher
> order functions. 

I don't think it would. Your proposed syntax is only useful in the case 
that the outer function has no doc string and there's no pre-processing 
or post-processing of the inner function, including decorators.

In practice, when I write higher order functions, I often do something 
like this example:

# untested
def spam_factory(n):
     """Factory returning decorators that print 'spam' n times."""
     msg = "spam " * n
     if n > 5:
         msg += 'WONDERFUL SPAM!!!'
     def decorator(func):
         """Print 'spam' %d times."""
         @functools.wraps(func)
         def f(*args, *kwargs):
             print msg
             return func(*args, **kwargs)
         return f
     decorator.__doc__ = decorator.__doc__ % n
     return decorator

Although the function as given is contrived, the basic structure 
(including doc strings, decorators, pre-processing and post-processing) 
is realistic, and your suggested syntax wouldn't be useful here.




-- 
Steven