feat(nullable): add map

Author: glennsl

src/Core__Nullable.mjs

@@ -1,5 +1,6 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
+import * as Curry from "rescript/lib/es6/curry.js";
 import * as Caml_option from "rescript/lib/es6/caml_option.js";
 
 function fromOption(option) {
@@ -28,9 +29,17 @@ function getExn(value) {
       };
 }
 
+function map(value, f) {
+  if (!(value == null)) {
+    return Caml_option.some(Curry._1(f, value));
+  }
+  
+}
+
 export {
   fromOption ,
   getWithDefault ,
   getExn ,
+  map ,
 }
 /* No side effect */

src/Core__Nullable.res

@@ -27,3 +27,9 @@ let getExn: t<'a> => 'a = value =>
   }
 
 external getUnsafe: t<'a> => 'a = "%identity"
+
+let map = (value, f) =>
+  switch value->toOption {
+  | Some(x) => Some(f(x))
+  | None => None
+  }