diff options
Diffstat (limited to 'aoc-2020-gleam/src/ext/listx.gleam')
| -rw-r--r-- | aoc-2020-gleam/src/ext/listx.gleam | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/aoc-2020-gleam/src/ext/listx.gleam b/aoc-2020-gleam/src/ext/listx.gleam index 2d4f4b6..8d20bd6 100644 --- a/aoc-2020-gleam/src/ext/listx.gleam +++ b/aoc-2020-gleam/src/ext/listx.gleam @@ -1,4 +1,6 @@ +import gleam/pair import gleam/iterator as iter +import gleam/result as res import ext/iteratorx as iterx pub fn count(list: List(a), satisfying predicate: fn(a) -> Bool) -> Int { @@ -18,3 +20,11 @@ fn set_helper(list: List(a), value: a, index: Int, counter: Int) -> List(a) { pub fn set(list: List(a), value: a, at index: Int) -> List(a) { set_helper(list, value, index, 0) } + +pub fn index_of(list: List(a), value: a) -> Result(Int, Nil) { + list + |> iter.from_list + |> iter.index + |> iter.find(one_that: fn(elem) { pair.second(elem) == value }) + |> res.map(with: pair.first) +} |