map.update uses option

4 files changed, 17 insertions, 9 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 39cf839..3e7306f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- The `map.update` function now uses `Option` rather than `Result`.
+
 ## v0.16.0 - 2021-06-17
 
 - The `list` module gains the `interleave`, `flat_map` and `transpose` functions.
diff --git a/src/gleam/iterator.gleam b/src/gleam/iterator.gleam
index ff2e020..25cc441 100644
--- a/src/gleam/iterator.gleam
+++ b/src/gleam/iterator.gleam
@@ -1,6 +1,7 @@
 if erlang {
   import gleam/list
   import gleam/map.{Map}
+  import gleam/option.{None, Option, Some}
 
   // Internal private representation of an Iterator
   type Action(element) {
@@ -712,7 +713,7 @@ if erlang {
   type SizedChunk(element) {
     Another(List(element), fn() -> Action(element))
     Last(List(element))
-    None
+    NoMore
   }
 
   fn next_sized_chunk(
@@ -723,7 +724,7 @@ if erlang {
     case continuation() {
       Stop ->
         case current_chunk {
-          [] -> None
+          [] -> NoMore
           remaining -> Last(list.reverse(remaining))
         }
       Continue(e, next) -> {
@@ -742,7 +743,7 @@ if erlang {
   ) -> fn() -> Action(List(element)) {
     fn() {
       case next_sized_chunk(continuation, count, []) {
-        None -> Stop
+        NoMore -> Stop
         Last(chunk) -> Continue(chunk, stop)
         Another(chunk, next_element) ->
           Continue(chunk, do_sized_chunk(next_element, count))
@@ -888,11 +889,11 @@ if erlang {
 
   fn update_group_with(
     el: element,
-  ) -> fn(Result(List(element), Nil)) -> List(element) {
+  ) -> fn(Option(List(element))) -> List(element) {
     fn(maybe_group) {
       case maybe_group {
-        Ok(group) -> [el, ..group]
-        Error(Nil) -> [el]
+        Some(group) -> [el, ..group]
+        None -> [el]
       }
     }
   }
diff --git a/src/gleam/map.gleam b/src/gleam/map.gleam
index ff8281d..7fd363f 100644
--- a/src/gleam/map.gleam
+++ b/src/gleam/map.gleam
@@ -1,5 +1,6 @@
 if erlang {
   import gleam/result
+  import gleam/option.{Option}
   import gleam/list
 
   /// A dictionary of keys and values.
@@ -279,10 +280,11 @@ if erlang {
   pub fn update(
     in map: Map(k, v),
     update key: k,
-    with fun: fn(Result(v, Nil)) -> v,
+    with fun: fn(Option(v)) -> v,
   ) -> Map(k, v) {
     map
     |> get(key)
+    |> option.from_result
     |> fun
     |> insert(map, key, _)
   }
diff --git a/test/gleam/map_test.gleam b/test/gleam/map_test.gleam
index 6f32c8f..d09a00a 100644
--- a/test/gleam/map_test.gleam
+++ b/test/gleam/map_test.gleam
@@ -2,6 +2,7 @@ if erlang {
   import gleam/string
   import gleam/should
   import gleam/map
+  import gleam/option.{None, Some}
 
   pub fn from_list_test() {
     [#(4, 0), #(1, 0)]
@@ -131,8 +132,8 @@ if erlang {
 
     let inc_or_zero = fn(x) {
       case x {
-        Ok(i) -> i + 1
-        Error(_) -> 0
+        Some(i) -> i + 1
+        None -> 0
       }
     }