Represents a set of unique values. So (Set Id) is a set of custom Id types and (Set String) works as usual.

Create an empty set.

Create a set with one value.

Insert a value into a set.

Remove a value from a set. If the value is not found, no changes are made.

Determine if a set is empty.

Determine if a value is in a set.

Determine the number of elements in a set.

Compare two sets for equality, ignoring insertion order. Sets are defined to be equal when they have identical keys where the keys are compared using the built-in equality operator.

You should almost never use the built-in equality operator to compare sets from this module since association lists have no canonical form.

Get the union of two sets. Keep all values.

Get the intersection of two sets. Keeps values that appear in both sets.

Get the difference between the first set and the second. Keeps values that do not appear in the second set.

Convert a set into a list, sorted from lowest to highest.

Convert a list into a set, removing any duplicates.

Map a function onto a set, creating a new set with no duplicates.

Fold over the values in a set, in order from lowest to highest.

Fold over the values in a set, in order from highest to lowest.

Only keep elements that pass the given test.

import Set exposing (Set)


numbers : Set Int
numbers =
    Set.fromList [ -2, -1, 0, 1, 2 ]


positives : Set Int
positives =
    Set.filter (\x -> x > 0) numbers


-- positives == Set.fromList [ 1, 2 ]

Create two new sets. The first contains all the elements that passed the given test, and the second contains all the elements that did not.