Typed Python?

[Ville Vainio]

>>>>> "Jacek" == Jacek Generowicz <jacek.generowicz at cern.ch> writes:

    Jacek> Ville Vainio <ville at spammers.com> writes:

    >> Only the academics seem to think Scheme is easier to learn
    >> than, say Python or even C. Students often disagree.

    Jacek> Sounds great; I bet it makes a lot of Python fans feel warm
    Jacek> and fuzzy inside. Unfortunately the claim is completely
    Jacek> unfounded.

    Jacek> You should take a look at what the TeachScheme people have
    Jacek> been doing, and what they seem to be achieving.

I took a look at the TeachScheme website. One example program in
particular caught my eye in http://www.teach-scheme.org/Talks/.

the Scheme version:

( define  ( guest  name  list )
     ( cond
          ( ( empty?  list )                        ?no                         )
          ( ( equal?   name  ( first  list ))     ?yes                          )
          (   else                                       ( guest  name  ( rest  list ))   ) ))   


C/C++:

------

#include <stdio.h>
typedef struct listCell * list;
struct listCell {
  int  first;
  list rest;
};
bool guest (int x, list l) {
  if (l == NULL)
    return false;
  else if (x == (l -> first))
    return true;
  else
    return guest (x, l -> rest);
}
int main (int argc, char ** argv) {
  list l1, l2, l3 = NULL;  int  x;
  l1 = (list) malloc (sizeof (struct listCell));
  l2 = (list) malloc (sizeof (struct listCell));
  l2 -> first = 3;  l2 -> rest = l3;
  l1 -> first = 2;  l1 -> rest = l2;
  scanf ("%d", &x);
  printf ("%d\n", member (x, l1));
}
----------

So they implement a linked list data type in C/C++ version, and use
the native/natural linked list (i.e. just a list) in Scheme. That's
kinda weasely road to take, don't you think? Especially if they use
this as marketing material for non-techies...

And here's the equally weaselish Python version, which they
unsurprisingly don't include:

-----------
def guest(name, list):
  return name in list
-----------

I'd like to see an example program, targeted at, say, 12 year olds,
where Scheme beats Python in simplicity (one that is not a compiler,
mind you ;-).

-- 
Ville Vainio   http://tinyurl.com/2prnb