Support unicode in env variables

Author: tranzystorekk

src/gleam/os.gleam

@@ -17,10 +17,10 @@ external fn os_unsetenv(key: CharList) -> Bool =
   "os" "unsetenv"
 
 external fn char_list_to_string(CharList) -> String =
-  "erlang" "list_to_binary"
+  "unicode" "characters_to_binary"
 
 external fn string_to_char_list(String) -> CharList =
-  "erlang" "binary_to_list"
+  "unicode" "characters_to_list"
 
 /// Returns all environment variables set on the system.
 pub fn get_env() -> Map(String, String) {

test/gleam/os_test.gleam

@@ -15,6 +15,13 @@ pub fn env_test() {
   |> should.equal(Error(Nil))
 }
 
+pub fn unicode_test() {
+  os.insert_env("GLEAM_UNICODE_TEST", "Iñtërnâtiônà£ißætiøn☃💩")
+  os.get_env()
+  |> map.get("GLEAM_UNICODE_TEST")
+  |> should.equal(Ok("Iñtërnâtiônà£ißætiøn☃💩"))
+}
+
 pub fn system_time_test() {
   let june_12_2020 = 1591966971
   { os.system_time(os.Second) > june_12_2020 }