Hi, On 02/24/2016 11:08 AM, Fumiaki Kinoshita wrote:
Thinking tuples of as multi-element containers is not recommended. A tuple (a, b) is, a pair of one 'a' and one 'b';
Which, to me, at least, very much sounds like a container of two elements? Seriosuly, if, as a result of tuples being instances of Functor and Foldable etc., the end result is confusion to the point that many no longer understand a tuple simply as a container of a certain number of elements, then that's another case in point against this whole design. (In particular the Foldable part: while I personally don't find the functor instances particularly compelling or useful, they seem less likely to seriously bite.)
as Foldable works on values pointed by the rightmost type argument, 1 should be the only reasonable result of 'length'.
data TwoThree a b = TwoThree a a b b b
What should 'length (TwoThree "Foo" "Bar" 0 1 2)' be?
A static type error, perhaps? (As indeed it will be unless the appropriate instances are made for TwoThree. But I am guessing we should understand TwoThree as a tuple here.)
Looking at only the expression, 5 might seem to make sense, but is not meaningful considering the type.
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