Extras.elm

module Extras exposing (..)

-- derived from http://stackoverflow.com/a/33625733/4496839
-- has less helper functions than the List.Extra version


indexOfhelper : List a -> a -> Int -> Maybe Int
indexOfhelper lst elem offset =
    case lst of
        [] ->
            Nothing

        x :: xs ->
            if x == elem then
                Just offset
            else
                indexOfhelper xs elem (offset + 1)


indexOf : List a -> a -> Maybe Int
indexOf lst element =
    indexOfhelper lst element 0



-- A lot of the time this default is fine


indexOfDefault : List a -> a -> Int
indexOfDefault lst element =
    indexOfhelper lst element 0
        |> Maybe.withDefault -1



-- from https://github.com/elm-community/list-extra


find : (a -> Bool) -> List a -> Maybe a
find predicate list =
    case list of
        [] ->
            Nothing

        first :: rest ->
            if predicate first then
                Just first
            else
                find predicate rest



-- from https://github.com/elm-community/maybe-extra


orElseLazy : (() -> Maybe a) -> Maybe a -> Maybe a
orElseLazy fma mb =
    case mb of
        Nothing ->
            fma ()

        Just _ ->
            mb