link nullable and add tests

Author: zth

src/Core__Nullable.res

@@ -1,4 +1,4 @@
-type t<'a> = Js.Nullable.t<'a>
+@unboxed type t<'a> = Js.Nullable.t<'a> = Present('a) | @as(null) Null | @as(undefined) Undefined
 
 external null: t<'a> = "#null"
 

src/Core__Nullable.resi

@@ -8,7 +8,8 @@ Primarily useful when interoping with JavaScript when you don't know whether you
 Type representing a nullable value. 
 A nullable value can be the value `'a`, `null` or `undefined`.
 */
-type t<'a> = Js.Nullable.t<'a>
+@unboxed
+type t<'a> = Js.Nullable.t<'a> = Present('a) | @as(null) Null | @as(undefined) Undefined
 
 /**
 The value `null`.

test/NullableTests.mjs

@@ -0,0 +1,55 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+import * as Test from "./Test.mjs";
+
+function shouldHandleNullableValues(param) {
+  var tNull = null;
+  var tUndefined = undefined;
+  var tPresent = "hello";
+  var tmp;
+  tmp = (tNull === null || tNull === undefined) && tNull === null ? true : false;
+  Test.run([
+        [
+          "NullableTests.res",
+          9,
+          15,
+          35
+        ],
+        "Should handle null"
+      ], tmp, (function (prim0, prim1) {
+          return prim0 === prim1;
+        }), true);
+  var tmp$1;
+  tmp$1 = (tUndefined === null || tUndefined === undefined) && tUndefined !== null ? true : false;
+  Test.run([
+        [
+          "NullableTests.res",
+          19,
+          15,
+          40
+        ],
+        "Should handle undefined"
+      ], tmp$1, (function (prim0, prim1) {
+          return prim0 === prim1;
+        }), true);
+  var tmp$2;
+  tmp$2 = tPresent === null || tPresent === undefined || tPresent !== "hello" ? false : true;
+  Test.run([
+        [
+          "NullableTests.res",
+          29,
+          15,
+          38
+        ],
+        "Should handle present"
+      ], tmp$2, (function (prim0, prim1) {
+          return prim0 === prim1;
+        }), true);
+}
+
+shouldHandleNullableValues(undefined);
+
+export {
+  shouldHandleNullableValues ,
+}
+/*  Not a pure module */

test/NullableTests.res

@@ -0,0 +1,39 @@
+open RescriptCore
+
+let shouldHandleNullableValues = () => {
+  let tNull: Nullable.t<string> = %raw("null")
+  let tUndefined: Nullable.t<string> = %raw("undefined")
+  let tPresent: Nullable.t<string> = %raw(`"hello"`)
+
+  Test.run(
+    __POS_OF__("Should handle null"),
+    switch tNull {
+    | Null => true
+    | Present(_) | Undefined => false
+    },
+    \"==",
+    true,
+  )
+
+  Test.run(
+    __POS_OF__("Should handle undefined"),
+    switch tUndefined {
+    | Undefined => true
+    | Present(_) | Null => false
+    },
+    \"==",
+    true,
+  )
+
+  Test.run(
+    __POS_OF__("Should handle present"),
+    switch tPresent {
+    | Present("hello") => true
+    | _ => false
+    },
+    \"==",
+    true,
+  )
+}
+
+shouldHandleNullableValues()

test/TestSuite.mjs

@@ -7,6 +7,7 @@ import * as ArrayTests from "./ArrayTests.mjs";
 import * as ErrorTests from "./ErrorTests.mjs";
 import * as PromiseTest from "./PromiseTest.mjs";
 import * as ResultTests from "./ResultTests.mjs";
+import * as NullableTests from "./NullableTests.mjs";
 
 var bign = TestTests.bign;
 
@@ -38,6 +39,8 @@ var forEachIfErrorDoNotCallFunction = ResultTests.forEachIfErrorDoNotCallFunctio
 
 var decodeJsonTest = JsonTests.decodeJsonTest;
 
+var shouldHandleNullableValues = NullableTests.shouldHandleNullableValues;
+
 export {
   bign ,
   TestError ,
@@ -54,5 +57,6 @@ export {
   forEachIfOkCallFunction ,
   forEachIfErrorDoNotCallFunction ,
   decodeJsonTest ,
+  shouldHandleNullableValues ,
 }
 /* IntTests Not a pure module */

test/TestSuite.res

@@ -5,3 +5,4 @@ include ArrayTests
 include IntTests
 include ResultTests
 include JsonTests
+include NullableTests