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Add List.update and List.updater

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Richard Feldman 2020-09-03 20:31:43 -04:00
parent 0bdc7f2f74
commit 5eeb41d5c0
1 changed files with 17 additions and 0 deletions
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compiler/builtins/docs/List.roc
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@ -215,6 +215,23 @@ mapOrCancel : List before, (before -> Result after err) -> Result (List after) e
## >>> List.mapOks [ "", "a", "bc", "", "d", "ef", "" ]
mapOks : List before, (before -> Result after *) -> List after
## Returns a list with the element at the given index having been transformed by
## the given function.
##
## For a version of this which gives you more control over when to perform
## the transformation, see #List.updater
##
## ## Performance notes
##
## In particular when updating nested collections, this is potentially much more
## efficient than using #List.get to obtain the element, transforming it,
## and then putting it back in the same place.
update : List elem, Len, (elem -> elem) -> List elem
## A more flexible version of #List.update, which returns an "updater" function
## that lets you delay performing the update until later.
updater : List elem, Len -> { elem, new : elem -> List elem }
## If all the elements in the list are #Ok, return a new list containing the
## contents of those #Ok tags. If any elements are #Err, return #Err.
allOks : List (Result ok err) -> Result (List ok) err