From 790a5af001ed64c05fc21269220936a8cb052ce5 Mon Sep 17 00:00:00 2001
From: jmagaram <justin@magaram.com>
Date: Mon, 20 Mar 2023 11:05:33 -0700
Subject: [PATCH 1/2] Result.forEach

---
 src/Core__Result.mjs  |  8 ++++++
 src/Core__Result.res  |  6 +++++
 src/Core__Result.resi | 12 +++++++++
 test/ResultTests.mjs  | 60 +++++++++++++++++++++++++++++++++++++++++++
 test/ResultTests.res  | 21 +++++++++++++++
 test/TestSuite.mjs    | 13 +++++++---
 test/TestSuite.res    |  1 +
 7 files changed, 118 insertions(+), 3 deletions(-)
 create mode 100644 test/ResultTests.mjs
 create mode 100644 test/ResultTests.res

diff --git a/src/Core__Result.mjs b/src/Core__Result.mjs
index 832ab968..fd9e5ffb 100644
--- a/src/Core__Result.mjs
+++ b/src/Core__Result.mjs
@@ -102,6 +102,13 @@ function cmp(a, b, f) {
   }
 }
 
+function forEach(r, f) {
+  if (r.TAG === /* Ok */0) {
+    return Curry._1(f, r._0);
+  }
+  
+}
+
 export {
   getExn ,
   mapWithDefault ,
@@ -112,5 +119,6 @@ export {
   isError ,
   eq ,
   cmp ,
+  forEach ,
 }
 /* No side effect */
diff --git a/src/Core__Result.res b/src/Core__Result.res
index 51032a64..423ae5a1 100644
--- a/src/Core__Result.res
+++ b/src/Core__Result.res
@@ -91,3 +91,9 @@ let cmpU = (a, b, f) =>
   }
 
 let cmp = (a, b, f) => cmpU(a, b, (. x, y) => f(x, y))
+
+let forEach = (r, f) =>
+  switch r {
+  | Ok(ok) => f(ok)
+  | Error(_) => ()
+  }
diff --git a/src/Core__Result.resi b/src/Core__Result.resi
index d1e6636d..3f03b7bd 100644
--- a/src/Core__Result.resi
+++ b/src/Core__Result.resi
@@ -197,3 +197,15 @@ let eq: (t<'a, 'c>, t<'b, 'd>, ('a, 'b) => bool) => bool
   ```
 */
 let cmp: (t<'a, 'c>, t<'b, 'd>, ('a, 'b) => int) => int
+
+/**
+`forEach(res, f)` runs the provided function `f` on the `Ok` value. If `res` is `Error`, nothing happens. 
+
+## Examples
+
+```rescript
+Result.forEach(Ok(3), Console.log) // Logs "3", returns ()
+Result.forEach(Error("x"), Console.log) // Does nothing, returns ()
+```
+*/
+let forEach: (t<'a, 'b>, 'a => unit) => unit
diff --git a/test/ResultTests.mjs b/test/ResultTests.mjs
new file mode 100644
index 00000000..837ad952
--- /dev/null
+++ b/test/ResultTests.mjs
@@ -0,0 +1,60 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+import * as Test from "./Test.mjs";
+import * as Caml_obj from "rescript/lib/es6/caml_obj.js";
+import * as Core__Result from "../src/Core__Result.mjs";
+
+var eq = Caml_obj.equal;
+
+function forEachIfOkCallFunction(param) {
+  var called = {
+    contents: []
+  };
+  Core__Result.forEach({
+        TAG: /* Ok */0,
+        _0: 3
+      }, (function (i) {
+          called.contents.push(i);
+        }));
+  Test.run([
+        [
+          "ResultTests.res",
+          12,
+          22,
+          72
+        ],
+        "forEach: if ok, call function with ok value once"
+      ], called.contents, eq, [3]);
+}
+
+forEachIfOkCallFunction(undefined);
+
+function forEachIfErrorDoNotCallFunction(param) {
+  var called = {
+    contents: []
+  };
+  Core__Result.forEach({
+        TAG: /* Error */1,
+        _0: 3
+      }, (function (i) {
+          called.contents.push(i);
+        }));
+  Test.run([
+        [
+          "ResultTests.res",
+          19,
+          22,
+          63
+        ],
+        "forEach: if error, do not call function"
+      ], called.contents, eq, []);
+}
+
+forEachIfErrorDoNotCallFunction(undefined);
+
+export {
+  eq ,
+  forEachIfOkCallFunction ,
+  forEachIfErrorDoNotCallFunction ,
+}
+/*  Not a pure module */
diff --git a/test/ResultTests.res b/test/ResultTests.res
new file mode 100644
index 00000000..0dbda319
--- /dev/null
+++ b/test/ResultTests.res
@@ -0,0 +1,21 @@
+open RescriptCore
+
+let eq = (a, b) => a == b
+
+// =======
+// forEach
+// =======
+
+let forEachIfOkCallFunction = () => {
+  let called = ref([])
+  Ok(3)->Result.forEach(i => called.contents->Array.push(i))
+  Test.run(__POS_OF__("forEach: if ok, call function with ok value once"), called.contents, eq, [3])
+}
+forEachIfOkCallFunction()
+
+let forEachIfErrorDoNotCallFunction = () => {
+  let called = ref([])
+  Error(3)->Result.forEach(i => called.contents->Array.push(i))
+  Test.run(__POS_OF__("forEach: if error, do not call function"), called.contents, eq, [])
+}
+forEachIfErrorDoNotCallFunction()
diff --git a/test/TestSuite.mjs b/test/TestSuite.mjs
index c968bd8f..2085495e 100644
--- a/test/TestSuite.mjs
+++ b/test/TestSuite.mjs
@@ -5,6 +5,7 @@ import * as TestTests from "./TestTests.mjs";
 import * as ArrayTests from "./ArrayTests.mjs";
 import * as ErrorTests from "./ErrorTests.mjs";
 import * as PromiseTest from "./PromiseTest.mjs";
+import * as ResultTests from "./ResultTests.mjs";
 
 var bign = TestTests.bign;
 
@@ -26,10 +27,14 @@ var Concurrently = PromiseTest.Concurrently;
 
 var panicTest = ErrorTests.panicTest;
 
-var eq = IntTests.eq;
-
 var $$catch = IntTests.$$catch;
 
+var eq = ResultTests.eq;
+
+var forEachIfOkCallFunction = ResultTests.forEachIfOkCallFunction;
+
+var forEachIfErrorDoNotCallFunction = ResultTests.forEachIfErrorDoNotCallFunction;
+
 export {
   bign ,
   TestError ,
@@ -41,7 +46,9 @@ export {
   Catching ,
   Concurrently ,
   panicTest ,
-  eq ,
   $$catch ,
+  eq ,
+  forEachIfOkCallFunction ,
+  forEachIfErrorDoNotCallFunction ,
 }
 /* IntTests Not a pure module */
diff --git a/test/TestSuite.res b/test/TestSuite.res
index 6277bf57..56266ed3 100644
--- a/test/TestSuite.res
+++ b/test/TestSuite.res
@@ -3,3 +3,4 @@ include PromiseTest
 include ErrorTests
 include ArrayTests
 include IntTests
+include ResultTests

From 9544a450baa950db7d6076b46efb03abf762a3d7 Mon Sep 17 00:00:00 2001
From: jmagaram <justin@magaram.com>
Date: Tue, 21 Mar 2023 14:04:28 -0700
Subject: [PATCH 2/2] Changelog - Result.forEach

---
 CHANGELOG.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 41f580aa..96d70a5b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## main
 
+### API changes
+
+- Add `Result.forEach` https://github.com/rescript-association/rescript-core/pull/116
+
 ## 0.2.0
 
 ### API changes