Darren Duncan writes:
> 1. I'm not sure if it is possible yet, but like Haskell et al ..., it
> should be possible to write a Perl 6 routine or program in a pure
> functional notation or paradigm, such that the entire routine body is
> a single expression, but that has named reusable sub-expressions.
I realize it isn't pure functional, but in Perl a C<do> block permits
arbitrary code to be treated as a single expression. Or to put it
another way round, you can use temporary variables inside the expression
that don't 'leak out' of it.
> For example, in pseudo-code:
>
> routine foo ($bar) {
> return
> with
> $bar * 17 -> $baz,
> $baz - 3 -> $quux,
> $baz / $quux;
> }
>
> This is instead of either of:
>
> routine foo ($bar) {
> return ($bar * 17) / ($bar * 17 - 3);
> }
That's obviously bad cos of the repetition.
> routine foo ($bar) {
> my $baz = $bar * 17;
> my $quux = $baz - 3;
> return $baz / $quux;
> }
But what does a functional form have over that? Or over the C<do>
version:
my $whatever
= do { my $baz = $bar * 17; my $quux = $baz - 3; $baz / $quux };
Sure there are variables. But in terms of how your brain thinks about
it is it any different from the functional version -- labels being
associated with intermediate parts of the calculation?
Smylers
