Refactor `first` to return a `Result`.

2 files changed, 12 insertions, 12 deletions

diff --git a/src/gleam/string.gleam b/src/gleam/string.gleam
index 2440e83..89cdc6c 100644
--- a/src/gleam/string.gleam
+++ b/src/gleam/string.gleam
@@ -740,26 +740,26 @@ pub fn to_option(s: String) -> Option(String) {
   }
 }
 
-/// Returns the first element in a grapheme and wraps it in an `Option(String)`.
-/// If the `String` is empty, it returns `None`. Otherwise, it returns
-/// `Some(String)`.
+/// Returns the first grapheme cluster in a given `String` and wraps it in a
+/// `Result(String, Nil)`. If the `String` is empty, it returns `Error(Nil)`.
+/// Otherwise, it returns `Ok(String)`.
 ///
 /// ## Examples
 ///
 /// ```gleam
 /// > first("")
-/// None
+/// Error(Nil)
 /// ```
 ///
 /// ```gleam
 /// > first("icecream")
-/// Some("i")
+/// Ok("i")
 /// ```
 ///
-pub fn first(s: String) -> Option(String) {
-  case length(s) {
-    0 -> None
-    _ -> Some(slice(s, 0, 1))
+pub fn first(s: String) -> Result(String, Nil) {
+  case pop_grapheme(s) {
+    Ok(#(first, _)) -> Ok(first)
+    Error(e) -> Error(e)
   }
 }
 
diff --git a/test/gleam/string_test.gleam b/test/gleam/string_test.gleam
index 31c93ad..56b50a0 100644
--- a/test/gleam/string_test.gleam
+++ b/test/gleam/string_test.gleam
@@ -368,15 +368,15 @@ pub fn to_option_test() {
 pub fn first_test() {
   ""
   |> string.first
-  |> should.equal(None)
+  |> should.be_error
 
   "gleam"
   |> string.first
-  |> should.equal(Some("g"))
+  |> should.equal(Ok("g"))
 
   "⭐️ Gleam"
   |> string.first
-  |> should.equal(Some("⭐️"))
+  |> should.equal(Ok("⭐️"))
 }
 
 pub fn last_test() {