roc/compiler/builtins/docs/Set.roc
2021-06-04 21:27:26 -04:00

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interface Set
exposes [ Set, empty, isEmpty, len, add, drop, map ]
imports []
## Set
## A Set is an unordered collection of unique elements.
Set elem : [ @Set elem ]
## An empty set.
empty : Set *
## Check
isEmpty : Set * -> Bool
len : Set * -> Nat
# TODO: removed `'` from signature because parser does not support it yet
# Original signature: `add : Set 'elem, 'elem -> Set 'elem`
## Make sure never to add a *NaN* to a [Set]! Becuase *NaN* is defined to be
## unequal to *NaN*, adding a *NaN* results in an entry that can never be
## retrieved or removed from the [Set].
add : Set elem, elem -> Set elem
## Drops the given element from the set.
# TODO: removed `'` from signature because parser does not support it yet
# Original signature: `drop : Set 'elem, 'elem -> Set 'elem`
drop : Set elem, elem -> Set elem
## Convert each element in the set to something new, by calling a conversion
## function on each of them. Then return a new set of the converted values.
##
## >>> Set.map {: -1, 1, 3 :} Num.negate
##
## >>> Set.map {: "", "a", "bc" :} Str.isEmpty
##
## `map` functions like this are common in Roc, and they all work similarly.
## See for example #Result.map, #List.map, and #Map.map.
# TODO: removed `'` from signature because parser does not support it yet
# Original signature: `map : Set 'elem, ('before -> 'after) -> Set 'after`
map : Set elem, (before -> after) -> Set after