Exts.List

Extensions to the core List library.

chunk : Int -> List a -> List (List a)

Split a list into chunks of length n.

Be aware that the last sub-list may be smaller than n-items long.

For example chunk 3 [1..10] => [[1,2,3], [4,5,6], [7,8,9], [10]]

mergeBy : (a -> comparable) -> List a -> List a -> List a

Merge two lists. The first argument is a function which returns the unique ID of each element. Where an element appears more than once, the last won wins.

singleton : a -> List a

Wrap a single item into a List.

maybeSingleton : Maybe a -> List a

Wrap a maybe item into a List. If the item is Nothing, the List is empty.

firstMatch : (a -> Bool) -> List a -> Maybe a

Find the first element in the List that matches the given predicate.

rest : List a -> List a

Like List.tail, but if the list is empty it returns an empty list rather than Nothing.

unique : List comparable -> List comparable

Return a new list with duplicates removed. Order is preserved.

exactlyOne : List a -> Result String a

Extract the first item from the List, demanding that there be exactly one element.

For example, Json.Decode.customDecoder string exactlyOne creates a decoder that expects a list of strings, where there is only one element in the List.

If you think that's weird, you haven't seen enough real-world JSON. ;-)

krisajenkins/elm-exts/25.12.0

Exts.List

Modules