Symbol module

Author: lpil

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## v1.0.0 - 2025-01-03
 
+- The symbol type and functions have been moved to a new `symbol` module.
 - Removed the `raceN` and `awaitN` functions from the `promise` module.
 - Removed the `map` module.
 - Removed the `type_of` function and `TypeOf` type from the `javascript` module.

src/gleam/javascript.gleam

@@ -0,0 +1,41 @@
+/// Symbols are special unique values in JavaScript.
+///
+/// For further information view the MDN documentation: 
+/// <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol>
+///
+pub type Symbol
+
+/// Creates a new symbol with the given description.
+///
+/// Symbols created with this function are "local", they are not in the global
+/// symbol registry.
+///
+/// For further information see the MDN documentation:
+/// <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/Symbol>
+///
+@external(javascript, "../../gleam_javascript_ffi.mjs", "new_symbol")
+pub fn new(description: String) -> Symbol
+
+/// Returns the symbol for the given key from the global symbol registry,
+/// creating and registering a new one if one did not already exist.
+///
+/// Uses the JavaScript `Symbol.for` internally.
+///
+/// For further information see the MDN documentation:
+/// <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/for>
+///
+@external(javascript, "../../gleam_javascript_ffi.mjs", "get_symbol")
+pub fn get_or_create_global(key: String) -> Symbol
+
+/// Get the description of the symbol, if it has one.
+///
+/// # Examples
+///
+/// ```gleam
+/// symbol.new("wibble")
+/// |> symbol.description
+/// // -> Ok("wibble")
+/// ```
+///
+@external(javascript, "../../gleam_javascript_ffi.mjs", "symbol_description")
+pub fn description(symbol: Symbol) -> Result(String, Nil)

src/gleam/javascript/symbol.gleam

@@ -27,9 +27,17 @@ export function object_from_entries(entries) {
   return Object.fromEntries(entries);
 }
 
+export function new_symbol(name) {
+  return Symbol(name);
+}
 export function get_symbol(name) {
   return Symbol.for(name);
 }
+export function symbol_description(symbol) {
+  const description = symbol.description;
+  if (symbol.description === undefined) return new Error(undefined);
+  return new Ok(description);
+}
 
 // A wrapper around a promise to prevent `Promise<Promise<T>>` collapsing into
 // `Promise<T>`.

src/gleam_javascript_ffi.mjs

@@ -0,0 +1,25 @@
+import gleam/javascript/symbol
+import gleeunit/should
+
+pub fn new_test() {
+  let name = "same name"
+
+  symbol.new(name)
+  |> should.not_equal(symbol.new(name))
+}
+
+pub fn get_or_create_global_test() {
+  let name = "same name"
+
+  symbol.get_or_create_global(name)
+  |> should.equal(symbol.get_or_create_global(name))
+
+  symbol.get_or_create_global(name)
+  |> should.not_equal(symbol.new(name))
+}
+
+pub fn description_test() {
+  symbol.new("wibble")
+  |> symbol.description
+  |> should.equal(Ok("wibble"))
+}