On 17 August 2013 19:11, Christopher Done
Anyone ever needed this? Me and John Wiegley were discussing a decent name for it, John suggested inv as in involution. E.g.
In terms of a decent name: as soon as I saw the subject, I thought you were somehow inverting a function :/ In terms of how useful it is, I don't think I tend to use such an idiom.
inv reverse (take 10) inv reverse (dropWhile isDigit) trim = inv reverse (dropWhile isSpace) . dropWhile isSpace
That seems to be the only use-case I've ever come across.
There's also this one:
co f g = f g . g
which means you can write
trim = co (inv reverse) (dropWhile isSpace)
but that's optimizing an ever rarer use-case.
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