John Fouhy wrote:
> On 15/05/06, w chun <[EMAIL PROTECTED]> wrote:
>> anyone know if list comps work the same way in haskell?
>
> Slightly not what you asked, but you can do some funky things with
> list comprehensions in Haskell.
>
> Check this out:
>
> fibs = 0 : 1 : [ a + b | (a, b) <- zip fibs (tail fibs)]
>
> The python translation would be something like:
>
> fibs = [0, 1] + [ a+b for (a, b) in zip(fibs, fibs[1:])]
>
> But you can't quite do that in python :-)
You can come pretty close with generators, though it hurts to think
about what is actually going on behind the scenes here:
In [1]: import itertools
In [2]: def fibs():
...: yield 0
...: yield 1
...: fib1 = fibs()
...: fib2 = fibs()
...: fib2.next()
...: for a, b in itertools.izip(fib1, fib2):
...: yield a+b
...:
...:
In [3]: f=fibs()
In [4]: [f.next() for i in range(10)]
Out[4]: [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]
Kent
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