Re: Haskell Foldable Wast

El 17 feb 2016, a las 14:03, John Wiegley escribió:

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amindfv writes:

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maximum(99, 0) = 0

I don't quite understand; are you saying you expect Foldable to treat a tuple as a 2-element list? If it did, would that better or worse?

And if it should, then what would you expect this to mean:

maximum("Hello", 0)

Or do you want both to be errors?

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 If I have a tuple foo and a list foo', I'd hope for an error if I write the wrong name, not silently acting wonky. This will cause real bugs. (Also I've seen newcomers accidentally "parenthesize" with functions, so writing "maximum(99,0)" could be an attempt to write "max 99 0") Part of the power of a type system is which program it rejects, and I'm arguing we're cluttering the space of valid programs. This isn't a criticism of the FTP in general (which I largely supported, and whose ship has sailed). It's about a few "wtf" instances which cause silent errors. Tom

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