Andreas Abel <

[hidden email]> writes:

> lurkup is essentially lookup returning a CPS-version (Church

> encoding) of Maybe a.

>

> type CMaybe a = forall r. r -> (a -> r) -> r

> lurkup' :: k -> Map k a -> CMaybe a

>

> Is it worth to add a new name for this (above the Fairbairn threshhold)?

I don’t think so :-)

> I am quite happy with writing stuff like

>

> fromMaybe d $ Map.lookup k m

There might be a case for a flipped infix version of this. I see

that there are several in various libraries including `orElse`

and (?:) more than once.

> On 2020-06-08 21:07, David Feuer wrote:

>> lurkup :: Ord k

>> => r -> (a -> r) -> k -> Map k a -> r

>> lurkup r f k = maybe r f . lookup k

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Jón Fairbairn

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