Hi all, I am currently about 3 side projects (small games) deep in Elm and the experience has been overally very good. I however encountered a few simple things I missed in the core libraries, so I would like to ask, if there is a reason to not have them there. If not, I'll be happy to file a pull request with them :-)
So here they are, in order of decreasing importance (IMHO) 1) List.get : Int -> List a -> Maybe a Just a way to get the nth element of a linked list in O(n) time. (the signature mimics that of Array.get). I know this exists in http://package.elm-lang.org/packages/circuithub/elm-list-extra/3.10.0/List-Extra but seems important enough to have it in the core. 2) Random.constant : a -> Generator a A generator that is not really a generator, but returns a fixed value. This is useful for composing generators with Random.map and Random.andThen or for the base case of recursive generators. An example use case is if I want to pick a value that is zero 50% percent of the time and 1-5 otherwise (happened in my game a few times) This one is already present in http://package.elm-lang.org/packages/mgold/elm-random-pcg/latest/Random-Pcg which, according to https://github.com/elm-lang/core/issues/724 should replace the core Random in the future, but why not add it now :-) generateValue : Bool -> Generator Float generateValue isZero = if isZero then Random.constant 0 else Random.float 1 5 Random.bool |> Random.andThen generateValue it also lets you write things like (which is probably not a very common use case, but came in handy for me): listOfGeneratorsToGeneratorOfList : List (Random.Generator a) -> Random.Generator (List a) listOfGeneratorsToGeneratorOfList listOfGenerators = case listOfGenerators of head :: tail -> Random.andThen (listOfGeneratorsToGeneratorOfList tail) (\list -> Random.map (\x -> x :: list) head) [] -> Random.constant [] currently, you can declare constant generator like this, but it seems stupid and wasteful: constant : a -> Random.Generator a constant value = Random.map (\_ -> value) Random.bool 3) Random.permutation : List a -> Generator (List a) This would simply pick a permutation of the original list at random. Might make sense to write this in javascript via converstion to array, as the O(n) algorithm (Knuth shuffle) for this does not seem to translate well into pure functional world... I currently do not see a purely functional implementation that is not O(n^2), but I'll be happy to be proven wrong :-) I understand that it is important to keep the core library slim (especially until dead code elimination is brought to Elm), so which of those you think should make the cut? Looking forward to your ideas Martin Černý -- You received this message because you are subscribed to the Google Groups "Elm Discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
