JavaScript module

4 files changed, 90 insertions, 2 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1c049cb..fe8e251 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,5 +2,8 @@
 
 ## Unreleased
 
-- The `array` module was created with the `Array(element)` type and `to_list`,
-  `from_list`, `map`, `fold`, `fold_right`, `get`, and `length` functions.
+- The `javascript/array` module was created with the `Array(element)` type and
+  `to_list`, `from_list`, `map`, `fold`, `fold_right`, `get`, and `length`
+  functions.
+- The `javascript` module was created with the `TypeOf`, and `Symbol` types, and
+  `find_symbol`, and `type_of` functions.
diff --git a/src/ffi.js b/src/ffi.js
index c0b2076..07e7b0f 100644
--- a/src/ffi.js
+++ b/src/ffi.js
@@ -1,4 +1,14 @@
 import { Ok, Error } from "./gleam.js";
+import {
+  UndefinedType,
+  ObjectType,
+  BooleanType,
+  NumberType,
+  BigIntType,
+  StringType,
+  SymbolType,
+  FunctionType,
+} from "./gleam/javascript.js";
 
 export function toArray(list) {
   return list.toArray();
@@ -23,3 +33,34 @@ export function reduceRight(thing, acc, fn) {
 export function index(thing, index) {
   return index in thing ? new Ok(thing[index]) : new Error(undefined);
 }
+
+export function object_from_entries(entries) {
+  return Object.fromEntries(entries);
+}
+
+export function type_of(value) {
+  switch (typeof value) {
+    case "undefined":
+      return new UndefinedType();
+    case "object":
+      return new ObjectType();
+    case "boolean":
+      return new BooleanType();
+    case "number":
+      return new NumberType();
+    case "bigint":
+      return new BigIntType();
+    case "string":
+      return new StringType();
+    case "symbol":
+      return new SymbolType();
+    case "function":
+      return new FunctionType();
+    default:
+      throw new globalThis.Error(`Unexpected typeof ${typeof value}`);
+  }
+}
+
+export function get_symbol(name) {
+  return Symbol.for(name);
+}
diff --git a/src/gleam/javascript.gleam b/src/gleam/javascript.gleam
new file mode 100644
index 0000000..590dece
--- /dev/null
+++ b/src/gleam/javascript.gleam
@@ -0,0 +1,19 @@
+// TODO: docs
+pub type TypeOf {
+  UndefinedType
+  ObjectType
+  BooleanType
+  NumberType
+  BigIntType
+  StringType
+  SymbolType
+  FunctionType
+}
+
+pub external type Symbol
+
+pub external fn type_of(value) -> TypeOf =
+  "../ffi.js" "type_of"
+
+pub external fn get_symbol(String) -> Symbol =
+  "../ffi.js" "get_symbol"
diff --git a/test/gleam/javascript_test.gleam b/test/gleam/javascript_test.gleam
new file mode 100644
index 0000000..81477d8
--- /dev/null
+++ b/test/gleam/javascript_test.gleam
@@ -0,0 +1,25 @@
+import gleam/javascript.{
+  BooleanType, FunctionType, NumberType, ObjectType, StringType, SymbolType, UndefinedType,
+}
+
+pub fn type_of_test() {
+  assert UndefinedType = javascript.type_of(Nil)
+  assert NumberType = javascript.type_of(1)
+  assert NumberType = javascript.type_of(1.1)
+  assert BooleanType = javascript.type_of(True)
+  assert BooleanType = javascript.type_of(False)
+  assert StringType = javascript.type_of("ok")
+  assert StringType = javascript.type_of("")
+  assert FunctionType = javascript.type_of(fn() { 1 })
+  assert FunctionType = javascript.type_of(fn(x) { x })
+  assert FunctionType = javascript.type_of(type_of_test)
+  assert FunctionType = javascript.type_of(Ok)
+  assert ObjectType = javascript.type_of(Ok(1))
+  assert ObjectType = javascript.type_of(Error("ok"))
+  assert SymbolType = javascript.type_of(javascript.get_symbol("Gleam"))
+}
+
+pub fn find_symbol_test() {
+  assert True = javascript.get_symbol("Gleam") == javascript.get_symbol("Gleam")
+  assert False = javascript.get_symbol("Gleam") == javascript.get_symbol("Lua")
+}