Add faster list functions

src/Vendor/ListExtra.elm

@@ -1,6 +1,7 @@
 module Vendor.ListExtra exposing
     ( find, last, uniquePairs
     , fastConcatMap
+    , orderIndependentMap, orderIndependentAppend, orderIndependentConcatMap, orderIndependentMapAppend, orderIndependentConcat, orderIndependentConcatMapAppend
     )
 
 {-| Functions taken from elm-community/list-extra.
@@ -8,11 +9,16 @@ module Vendor.ListExtra exposing
 These were used so that we wouldn't have dependency conflicts when
 elm-community/list-extra would release a new major version.
 
+This also includes a few custom functions
+
 
 # List functions
 
 @docs find, last, uniquePairs
 
+@docs fastConcatMap
+@docs orderIndependentMap, orderIndependentAppend, orderIndependentConcatMap, orderIndependentMapAppend, orderIndependentConcat, orderIndependentConcatMapAppend
+
 -}
 
 
@@ -64,3 +70,46 @@ uniquePairs xs =
 fastConcatMap : (a -> List b) -> List a -> List b
 fastConcatMap fn list =
     List.foldr (\item acc -> fn item ++ acc) [] list
+
+
+{-| Version of List.map that doesn't care about order.
+-}
+orderIndependentMap : (a -> b) -> List a -> List b
+orderIndependentMap fn list =
+    List.foldl (\element acc -> fn element :: acc) [] list
+
+
+{-| Version of List.append that doesn't care about order.
+-}
+orderIndependentAppend : List a -> List a -> List a
+orderIndependentAppend left right =
+    List.foldl (::) right left
+
+
+{-| Version of "List.append (List.map fn left) right" that doesn't care about order.
+-}
+orderIndependentMapAppend : (a -> b) -> List a -> List b -> List b
+orderIndependentMapAppend fn left right =
+    List.foldl (\element acc -> fn element :: acc) right left
+
+
+{-| Version of "(List.concatMap fn left) ++ right" that doesn't care about order.
+-}
+orderIndependentConcatMapAppend : (a -> List b) -> List a -> List b -> List b
+orderIndependentConcatMapAppend fn left right =
+    List.foldl (\item acc -> orderIndependentAppend (fn item) acc) right left
+
+
+orderIndependentConcat : List (List a) -> List a
+orderIndependentConcat list =
+    case list of
+        [] ->
+            []
+
+        firstElement :: rest ->
+            List.foldl (\subList acc -> orderIndependentAppend subList acc) firstElement rest
+
+
+orderIndependentConcatMap : (a -> List b) -> List a -> List b
+orderIndependentConcatMap fn list =
+    List.foldl (\item acc -> orderIndependentAppend (fn item) acc) [] list