65 lines
2.1 KiB
Elm
65 lines
2.1 KiB
Elm
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module Set (empty,singleton,insert,remove
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,member
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,foldl,foldr,map
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,union,intersect,diff
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,toList,fromList
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) where
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import Dict as Dict
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import List as List
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type Set t = Dict t ()
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-- Create an empty set.
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empty : Set (Comparable k)
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empty = Dict.empty
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-- Create a set with one value.
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singleton : Comparable k -> Set (Comparable k)
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singleton k = Dict.singleton k ()
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-- Insert a value into a set.
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insert : Comparable k -> Set (Comparable k) -> Set (Comparable k)
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insert k = Dict.insert k ()
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-- Remove a value from a set. If the value is not found, no changes are made.
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remove : Comparable k -> Set (Comparable k) -> Set (Comparable k)
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remove = Dict.remove
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-- Determine if a value is in a set.
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member : Comparable k -> Set (Comparable k) -> Bool
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member = Dict.member
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-- Get the union of two sets. Keep all values.
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union : Set (Comparable k) -> Set (Comparable k) -> Set (Comparable k)
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union = Dict.union
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-- Get the intersection of two sets. Keeps values that appear in both sets.
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intersect : Set (Comparable k) -> Set (Comparable k) -> Set (Comparable k)
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intersect = Dict.intersect
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-- Get the difference between the first set and the second. Keeps values
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-- that do not appear in the second set.
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diff : Set (Comparable k) -> Set (Comparable k) -> Set (Comparable k)
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diff = Dict.diff
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-- Convert a set into a list.
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toList : Set (Comparable k) -> [Comparable k]
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toList = Dict.keys
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-- Convert a list into a set, removing any duplicates.
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fromList : [Comparable k] -> Set (Comparable k)
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fromList xs = List.foldl insert empty xs
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-- Fold over the values in a set, in order from lowest to highest.
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foldl : (Comparable a -> b -> b) -> b -> Set (Comparable a) -> b
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foldl f b s = Dict.foldl (\k _ b -> f k b) b s
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-- Fold over the values in a set, in order from highest to lowest.
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foldr : (Comparable a -> b -> b) -> b -> Set (Comparable a) -> b
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foldr f b s = Dict.foldr (\k _ b -> f k b) b s
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-- Map a function onto a set, creating a new set with no duplicates.
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map : (Comparable a -> Comparable b) -> Set (Comparable a) -> Set (Comparable b)
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map f s = fromList (List.map f (toList s))
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