clamp function in base

[Carter Schonwald]

actually, if you look at the associated ticket, we have a version of clamp
that gives the right way to derive the onesided behaviors for even floating
point! (and has the correct / desirable behavior in the presence of NANs! )

On Wed, Aug 26, 2020 at 8:38 PM Jon Purdy <evincarofautumn at gmail.com> wrote:

> I’m also strongly for ‘clamp :: (Ord a) => (a, a) -> a -> a’.
>
> Even if we don’t resolve it now, I do want to mention that, in discussing
> this with some acquaintances recently, we agreed that one-sided clamps
> likely warrant a home in ‘Data.Ord’ as well:
>
> atLeast :: (Ord a) => a -> a -> a
> atLeast = max
> {-# INLINE atLeast #-}
>
> atMost :: (Ord a) => a -> a -> a
> atMost = min
> {-# INLINE atMost #-}
>
> clamp :: (Ord a) => (a, a) -> a -> a
> clamp (lower, upper) = atLeast lower . atMost upper
>
> While their implementations are identical to ‘max’ and ‘min’, semantically
> they privilege their arguments differently, serving as documentation of
> intent in code like ‘nonnegative = fmap (atLeast 0)’. The hope is that this
> may help reduce bugs caused by the common error of mixing up ‘min’ and
> ‘max’, owing to the unfortunate false friendship between “at least/most”
> and “the least/most”.
>
>
> On Sun, Aug 16, 2020 at 2:43 AM Henning Thielemann <
> lemming at henning-thielemann.de> wrote:
>
>>
>> On Fri, 14 Aug 2020, Sandy Maguire wrote:
>>
>> > It seems to me that base is missing the very standard function `clamp
>> :: Ord a => a -> a -> a -> a`:
>> >
>> > ```haskell
>> > clamp :: Ord a => a -> a -> a -> a
>> > clamp low high = min high .max low
>> > ```
>>
>>
>>
>> https://hackage.haskell.org/package/utility-ht-0.0.15/docs/Data-Ord-HT.html#v:limit
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