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Re: functional programming: scan function

by ikegami (Patriarch)
on Mar 12, 2009 at 20:20 UTC ( #750252=note: print w/replies, xml ) Need Help??

in reply to functional programming: scan function

The expensive recursion can be optimized away. Also, you might also want to specify the "&" prototype to also allow map-like syntax.
sub scanl(&@) { my ($f, @rv) = @_; $rv[$_] = $f->($rv[$_-1], $rv[$_]) for 1..$#rv; return @rv; } my @rv = scanl \&divide, 64, 4,2,4; -or- my @rv = scanl { $_[0] / $_[1] } 64, 4,2,4;

Finally, you could use $a and $b instead of $_[0] and $_[1], but that would prevent the use of existing functions directly. If that's not a problem, using $a and $b can be done by assigning references to *$ap and *$bp after doing

my $pkg = caller(); my $ap = do { no strict 'refs'; \*{$pkg.'::a'} }; local *$ap; my $bp = do { no strict 'refs'; \*{$pkg.'::b'} }; local *$bp;

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