Re: Haskell Foldable Wast

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amindfv writes:

I wouldn't expect a 2-tuple to be Foldable, particularly if

length (1, 2) = 1 fold ("foo", "bar") = "bar" toList (3,4) = [4] elem 1 (1,2) = False etc, etc

I think the fact that toList (3,4) has a meaning that is not obvious to the layman is a teaching matter. I read (x,4), in a Foldable context, as an "annotated 4", and not as some kind of shorthand for a two-element collection. My gut feeling is that the similarity to lists here is a specious argument; and that of all the things that confuse newcomers, restricting our standard library to avoid this scenario is energy spent in the wrong place. -- John Wiegley GPG fingerprint = 4710 CF98 AF9B 327B B80F http://newartisans.com 60E1 46C4 BD1A 7AC1 4BA2