Reduce iterations in concatenate! #946
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This commit should reduce the amount of iterations in concatenate to N where N is the sum of the lengths of the input lists. The previous implementation iterated from the beginning in each concatenation because of `last-pair`. This implementation is significantly faster in this extreme case: (concatenate! `(,(iota 50000) ,@(map list (iota 500)))) >> Previous implementation: real 0m0.671s user 0m0.658s sys 0m0.013s >> This implementation: real 0m0.175s user 0m0.174s sys 0m0.001s The tests is done using `time`, which is not reliable at all, but using `(trace last-pair)` shows accurately what happens with the iterations.
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This commit should reduce the amount of iterations in concatenate to N where N is the sum of the lengths of the input lists.
The previous implementation iterated from the beginning in each concatenation because of
last-pair.This implementation is significantly faster in this extreme case:
Previous implementation:
real 0m0.671s
user 0m0.658s
sys 0m0.013s
This implementation:
real 0m0.175s
user 0m0.174s
sys 0m0.001s
The tests is done using
time, which is not reliable at all, but using(trace last-pair)shows accurately what happens with the iterations.