18+ goldstein, 6 months ago

some random examples of weird footguny semantics in Raku:

my @arr = (2, 3);<br></br>reduce &[+], 1, @arr;<br></br>

is 3 (list gets reinterpreted as a scalar). you need to use |@arr for it to work.

reduce &[(&)], ();<br></br>

(identity element for set intersection) is an empty set for some reason.

Set.new((1, 2), (3, 4)) (&) Set.new((3, 4), (5, 6))<br></br>

is an empty set (sets use comparison by identity, so all the lists are considered different).

set((1, 2), (3, 4))<br></br>

is a set of four numbers 1, 2, 3, 4, set flattens its arguments, while Set.new does not.

sequences like x...^y and (x..^y).reverse are either not actually lazy, or just really slow, not sure which one.

18+ samebchase, 6 months ago

@goldstein Hmm, even in the official documentation it seems to require the | (slip) operator. https://docs.raku.org/routine/reduce

Could any experienced Rakoon let us know why this is necessary?

#rakulang