In defence of the two-namespace rule

[Colin J. Williams]

I recognize that most of this thread deals with deeper issues,
see the later posting by Tim Peters, but I would like to focus
on the list and one of its operations.

Quinn Dunkan wrote:
> 
> A curried function always takes one argument.  If it needs more values to
> 'finish', it returns a closure which will accept the next arg.  In python:
> 
> >>> def add(a):
> ...    return lambda b, a=a: a + b
> ...
> >>> add(4)
> <function <lambda> at 100b41f8>
> >>> add(4)(5)
> 9
> 
> A simple example of how this can be useful:
> 
> >>> map(add(5), range(5))
> [5, 6, 7, 8, 9]
> 
Wouldn't it be nice if we could write this as:

              5 + range(5) or 
              range(5) + 5?

Are we not complicating things by using '+' to mean addition in
most cases but catenation in the case of a list?

Colin W.

> Many functional languages such as the ml family and haskell have all functions
> curried by default, including +, *, etc. (there are no two-argument
> functions... of course, you could pass a _single_ tuple of two elements :))
> 
> Hugs> map (5+) [0..4]
> [5,6,7,8,9]
> 
> Whenever you know some args for a function now, and the rest later, you can
> partially apply it and toss the closure around.  It's very useful if your
> brain is working in the appropriate mode.