Well, in unary, summing is as simple as concatenating. And Perl has a built-in decimal-to-unary converter (the x operator), as well as a built-in unary-to-decimal converter (the length function). Putting all this together: 
my @list = (1, 2, 3, 4, 5);
print length join "", map{"1" x $_} @list; #prints 15

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But your implementation sure is fun :-) EDIT: Look at tye's code instead. This one is stupid. Don't know what I had in mind when I wrote 'length join "", '.

In reply to Re: (almost) foldl by Grimy
in thread (almost) foldl by dk

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