Same fringe: Difference between revisions

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m (→‎{{header|Perl 6}}: useless newline)
(→‎{{header|Perl 6}}: the gather {*} thing does not work anymore for some reason)
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{{Works with|Rakudo|#67 ("Bicycle")}}
Unlike in Perl 5, where <tt>=></tt> is just a synonym for comma, in Perl 6 it creates a true Pair object. So here we use Pair objects for our "cons" cells, just as if we were doing this in Lisp. We use the <tt>gather/take</tt> construct to harvest the leaves lazily as the elements are visited with a standard recursive algorithm, using multiple dispatch to differentiate nodes from leaves. The <tt>eqv</tt> value equivalence is applied to the two lists in parallel.
<lang perl6>protosub samefringe fringe($a, $b) { gatherfringe($a) {*}eqv fringe($b) }
multisub fringe (Pair $nodetree) { fringe $_ for $node.kv }
multi fringe(Anysub fringey (Pair $leafnode) { takefringey $_ for $leafnode.kv; }
multi sub fringey ( Any $leaf) { take $leaf; }
 
gather fringey $tree;
}
 
sub samefringe ($a, $b) { fringe($a) eqv fringe($b) }</lang>
Testing:
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