Haskell like (c:cs) syntax

[Paul Rubin]

"Stefan Niemann" <stefan at 3niemann.de> writes:
> Is there a pattern matching construct in Python like (head : tail), meaning 
> 'head' matches the first element of a list and 'tail' matches the rest? I 
> could not find this in the Python documentation.

Python's lists are actually linear arrays.  You can subscript them,
i.e. x[0] is the first element, and slice them, i.e. x[1:] is all
elements after the first.  Note that x[1:] actually makes a new
array and copies all the elements of x.  

Normally in Python one writes iterative loops rather than recursing
or folding over a list:

    for a in x:
      print a

so slicing isn't that common. 

Python also has something called generators which are sort of like
Haskell's lazy-evaluation lists.  They often make it possible to
program in a Haskell-like style.  Note however that they are mutable
objects, i.e. using g.next() to get the next element of a generator
actually updates the generator's internal state.  This can lead to a
bunch of subtle pitfalls if you're not careful, but overall they are a
very useful feature.