Proposal: alpha-rename the type signatures of foldl, foldl', and scanl to be consistent with foldr and scanr
conrad at metadecks.org
Mon Oct 15 01:58:48 CEST 2012
On 15 October 2012 03:28, Simon Hengel <sol at typeful.net> wrote:
> On Sun, Oct 14, 2012 at 09:00:18PM +0200, Gábor Lehel wrote:
>> On Sun, Oct 14, 2012 at 8:47 PM, Dan Burton <danburton.email at gmail.com> wrote:
>> > At the risk of useless bikeshedding... might I suggest "r" as a mnemonic for
>> > "result"?
>> > foldl :: (a -> r -> r) -> r -> [a] -> r
>> > foldr :: (r -> a -> r) -> r -> [a] -> r
>> > -- Dan Burton
>> 'r' is the version I originally used myself (see reddit). But then you
>> have to change the foldrs too, and quite possibly a lot of other
>> functions, and get dragged into a big discussion over when is 'r' a
>> better mnemonic than 'b' and when is it not.
>> Simply swapping 'a' and 'b' in the left folds captures most of the
>> benefit for least cost.
>> Same goes for most of the other suggestions I have seen (I don't find
>> the existing signatures actively confusing, merely suboptimal), but if
>> sentiment is overwhelmingly in favor of making further changes I can
>> be swayed. For now I wanted to propose a minimal change with the best
>> chance of attracting a broad consensus.
> I'm in favor of the simple change, so +1 ;)
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