Merge pull request #6 from garyb/fromFoldableWithIndex

Add `fromFoldableWithIndex` for `Map`

Author: garyb

src/Data/Map.purs

@@ -5,7 +5,7 @@ module Data.Map
 
 import Prelude
 
-import Data.Map.Internal (Map, alter, checkValid, delete, empty, filter, filterKeys, filterWithKey, findMax, findMin, foldSubmap, fromFoldable, fromFoldableWith, insert, isEmpty, isSubmap, lookup, lookupGE, lookupGT, lookupLE, lookupLT, member, pop, showTree, singleton, size, submap, toUnfoldable, toUnfoldableUnordered, union, unionWith, unions, difference, update, values, mapMaybeWithKey, mapMaybe)
+import Data.Map.Internal (Map, alter, checkValid, delete, empty, filter, filterKeys, filterWithKey, findMax, findMin, foldSubmap, fromFoldable, fromFoldableWith, fromFoldableWithIndex, insert, isEmpty, isSubmap, lookup, lookupGE, lookupGT, lookupLE, lookupLT, member, pop, showTree, singleton, size, submap, toUnfoldable, toUnfoldableUnordered, union, unionWith, unions, difference, update, values, mapMaybeWithKey, mapMaybe)
 import Data.Set (Set)
 import Unsafe.Coerce (unsafeCoerce)
 

src/Data/Map/Internal.purs

@@ -20,6 +20,7 @@ module Data.Map.Internal
   , submap
   , fromFoldable
   , fromFoldableWith
+  , fromFoldableWithIndex
   , toUnfoldable
   , toUnfoldableUnordered
   , delete
@@ -46,7 +47,7 @@ import Prelude
 
 import Data.Eq (class Eq1)
 import Data.Foldable (foldl, foldMap, foldr, class Foldable)
-import Data.FoldableWithIndex (class FoldableWithIndex, foldrWithIndex)
+import Data.FoldableWithIndex (class FoldableWithIndex, foldlWithIndex, foldrWithIndex)
 import Data.FunctorWithIndex (class FunctorWithIndex, mapWithIndex)
 import Data.List (List(..), (:), length, nub)
 import Data.List.Lazy as LL
@@ -555,6 +556,10 @@ fromFoldableWith f = foldl (\m (Tuple k v) -> alter (combine v) k m) empty where
   combine v (Just v') = Just $ f v v'
   combine v Nothing = Just v
 
+-- | Convert any indexed foldable collection into a map.
+fromFoldableWithIndex :: forall f k v. Ord k => FoldableWithIndex k f => f v -> Map k v
+fromFoldableWithIndex = foldlWithIndex (\k m v -> insert k v m) empty
+
 -- | Convert a map to an unfoldable structure of key/value pairs where the keys are in ascending order
 toUnfoldable :: forall f k v. Unfoldable f => Map k v -> f (Tuple k v)
 toUnfoldable m = unfoldr go (m : Nil) where