derive ‘size’ from ‘reduce’ #61
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@davidchambers Tuple es well as These might return unpredictable result. technically you can define size for betraversables too :d (but we don't have bitraversable in FL) |
davidchambers
commented
Jun 15, 2017
| eq(Z.size(Identity('quux')), 1); | ||
| eq(Z.size(Nothing), 0); | ||
| eq(Z.size(Just(0)), 1); | ||
| eq(Z.size(Tuple('abc', 123)), 1); |
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Tuple […] might return unpredictable result.
I agree that this is surprising initially, but it seems correct. Haskell agrees:
> length ("abc", 123)
1What do you suggest, @safareli?
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It's not unpredictable if the user is familiar with how reduce works for their data type. Foldable is in the signature after all.
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reduce works for their data type
Exactly!
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See sanctuary-js/sanctuary#414 for prior discussion.