Add Dict.mapValues

Author: Bart Schuurmans

src/Core__Dict.mjs

@@ -17,9 +17,18 @@ function forEachWithKey(dict, f) {
       });
 }
 
+function mapValues(dict, f) {
+  var target = {};
+  forEachWithKey(dict, (function (value, key) {
+          target[key] = f(value);
+        }));
+  return target;
+}
+
 export {
   $$delete$1 as $$delete,
   forEach ,
   forEachWithKey ,
+  mapValues ,
 }
 /* No side effect */

src/Core__Dict.res

@@ -31,3 +31,11 @@ let forEach = (dict, f) => {
 let forEachWithKey = (dict, f) => {
   dict->toArray->Core__Array.forEach(((key, value)) => f(value, key))
 }
+
+let mapValues = (dict, f) => {
+  let target = make()
+  dict->forEachWithKey((value, key) => {
+    target->set(key, f(value))
+  })
+  target
+}

src/Core__Dict.resi

@@ -220,3 +220,17 @@ dict->Dict.forEachWithKey((value, key) => {
 ```
 */
 let forEachWithKey: (t<'a>, ('a, string) => unit) => unit
+
+/**
+`mapValues(dictionary, f)` returns a new dictionary with the same keys, and `f` applied to each value in the original dictionary.
+
+## Examples
+
+```rescript
+let dict = Dict.fromArray([("key1", 1), ("key2", 2)])
+
+dict->Dict.mapValues(v => v + 10)->Dict.toArray // [("key1", 11), ("key2", 12)]
+dict->Dict.mapValues(Int.toString)->Dict.toArray // [("key1", "1"), ("key2", "2")]
+```
+*/
+let mapValues: (t<'a>, 'a => 'b) => t<'b>