On Sat, May 19, 2007 at 04:10:29PM +0100, Jon Fairbairn wrote:
[...]
>
> > foldl f z l = case l of
> (x:xs) -> foldl f (f z x) xs
> [] -> z
>
> which reveals that foldl in the RHS isn't really the
> leftmost outermost function, but case is -- the tail call is
> to case. It happens that case is a kind of function that
> makes a choice -- it returns one of its arguments but
> doesn't do anything more to it. In a strict language only
> some predefined operators like case and if have this
> property, but lazy languages allow the definition of new
> ones, which is why we need more care when thinking about
> tail calls.
By definition, tail recursive function is recursive function in which
the value returned from a recursive call is immediately returned without
modification as value of the top-level invocation, which is true for
foldl defined as above.
>
> --
> Jón Fairbairn [EMAIL PROTECTED]
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