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Switch to a tail recursive version of uniqueBy

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This commit is contained in:
Danila Fedorin 2019-08-31 23:00:52 -07:00
parent f6ce669fb4
commit b23c80f463
1 changed files with 9 additions and 7 deletions
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16
src/Scylla/Sync.elm
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@ -268,15 +268,17 @@ groupBy f xs =
in in
List.foldl (\v acc -> Dict.update (f v) (update v) acc) Dict.empty xs List.foldl (\v acc -> Dict.update (f v) (update v) acc) Dict.empty xs
uniqueByRecursive : (a -> comparable) -> List a -> Set comparable -> List a uniqueByTailRecursive : (a -> comparable) -> List a -> Set comparable -> List a -> List a
uniqueByRecursive f l s = case l of uniqueByTailRecursive f l s acc =
x::tail -> if Set.member (f x) s case l of
then uniqueByRecursive f tail s x::tail ->
else x::uniqueByRecursive f tail (Set.insert (f x) s) if Set.member (f x) s
[] -> [] then uniqueByTailRecursive f tail s acc
else uniqueByTailRecursive f tail s (x::acc)
[] -> acc
uniqueBy : (a -> comparable) -> List a -> List a uniqueBy : (a -> comparable) -> List a -> List a
uniqueBy f l = uniqueByRecursive f l Set.empty uniqueBy f l = uniqueByTailRecursive f l Set.empty []
findFirst : (a -> Bool) -> List a -> Maybe a findFirst : (a -> Bool) -> List a -> Maybe a
findFirst cond l = case l of findFirst cond l = case l of