@@ -1,6 +1,6 @@
1module Data.SortedMap
1module Data.SortedMap
3−-- TODO: write merge and split
3+-- TODO: write split
6data Tree : Nat -> (k : Type) -> Type -> Ord k -> Type where
6data Tree : Nat -> (k : Type) -> Type -> Ord k -> Type where
@@ -214,6 +214,10 @@ insert k v (M _ t) =
214 Left t' => (M _ t')
214 Left t' => (M _ t')
215 Right t' => (M _ t')
215 Right t' => (M _ t')
218+insertFrom : Foldable f => f (k, v) -> SortedMap k v -> SortedMap k v
219+insertFrom = flip $ foldl $ flip $ uncurry insert
218delete : k -> SortedMap k v -> SortedMap k v
222delete : k -> SortedMap k v -> SortedMap k v
219delete _ Empty = Empty
223delete _ Empty = Empty
@@ -235,6 +239,16 @@ toList : SortedMap k v -> List (k, v)
235toList Empty = []
239toList Empty = []
236toList (M _ t) = treeToList t
240toList (M _ t) = treeToList t
242+||| Gets the keys of the map.
244+keys : SortedMap k v -> List k
245+keys = map fst . toList
247+||| Gets the values of the map. Could contain duplicates.
249+values : SortedMap k v -> List v
250+values = map snd . toList
238treeMap : (a -> b) -> Tree n k a o -> Tree n k b o
252treeMap : (a -> b) -> Tree n k a o -> Tree n k b o
239treeMap f (Leaf k v) = Leaf k (f v)
253treeMap f (Leaf k v) = Leaf k (f v)
240treeMap f (Branch2 t1 k t2) = Branch2 (treeMap f t1) k (treeMap f t2)
254treeMap f (Branch2 t1 k t2) = Branch2 (treeMap f t1) k (treeMap f t2)
@@ -245,3 +259,40 @@ export
245implementation Functor (SortedMap k) where
259implementation Functor (SortedMap k) where
246 map _ Empty = Empty
260 map _ Empty = Empty
247 map f (M n t) = M _ (treeMap f t)
261 map f (M n t) = M _ (treeMap f t)
263+||| Merge two maps. When encountering duplicate keys, using a function to combine the values.
264+||| Uses the ordering of the first map given.
266+mergeWith : (v -> v -> v) -> SortedMap k v -> SortedMap k v -> SortedMap k v
267+mergeWith f x y = insertFrom inserted x where
268+ inserted : List (k, v)
271+ let v' = (maybe id f $ lookup k x) v
274+||| Merge two maps using the Semigroup (and by extension, Monoid) operation.
275+||| Uses mergeWith internally, so the ordering of the left map is kept.
277+merge : Semigroup v => SortedMap k v -> SortedMap k v -> SortedMap k v
278+merge = mergeWith (<+>)
280+||| Left-biased merge, also keeps the ordering specified by the left map.
282+mergeLeft : SortedMap k v -> SortedMap k v -> SortedMap k v
283+mergeLeft = mergeWith const
285+-- TODO: is this the right variant of merge to use for this? I think it is, but
286+-- I could also see the advantages of using `mergeLeft`. The current approach is
287+-- strictly more powerful I believe, because `mergeLeft` can be emulated with
288+-- the `First` monoid. However, this does require more code to do the same
291+Semigroup v => Semigroup (SortedMap k v) where
294+||| For `neutral <+> y`, y is rebuilt in `Ord k`, so this is not a "strict" Monoid.
295+||| However, semantically, it should be equal.
297+(Ord k, Semigroup v) => Monoid (SortedMap k v) where