result.replace

2 files changed, 67 insertions, 6 deletions

diff --git a/src/gleam/result.gleam b/src/gleam/result.gleam
index cd80e2d..c774219 100644
--- a/src/gleam/result.gleam
+++ b/src/gleam/result.gleam
@@ -240,18 +240,61 @@ pub fn lazy_or(
 /// If any element is `Error` then returns the first error.
 ///
 /// ## Examples
-///    > all([Ok(1), Ok(2)])
-///    Ok([1, 2])
 ///
-///    > all([Ok(1), Error("e")])
-///    Error("e")
+/// ```gleam
+/// > all([Ok(1), Ok(2)])
+/// Ok([1, 2])
+/// ```
+///
+/// ```gleam
+/// > all([Ok(1), Error("e")])
+/// Error("e")
+/// ```gleam
+///
 pub fn all(results: List(Result(a, e))) -> Result(List(a), e) {
   list.try_map(results, fn(x) { x })
 }
 
+/// Replace the value within a result
+///
+/// ## Examples
+///
+/// ```gleam
+/// > replace(Ok(1), Nil)
+/// Ok(Nil)
+/// ```
+///
+/// ```gleam
+/// > replace(Error(1), Nil)
+/// Error(1)
+/// ```
+///
+pub fn replace(result: Result(a, e), value: b) -> Result(b, e) {
+  case result {
+    Ok(_) -> Ok(value)
+    Error(error) -> Error(error)
+  }
+}
+
+/// Replace the error within a result
+///
+/// ## Examples
+///
+/// ```gleam
+/// > replace_error(Error(1), Nil)
+/// Error(Nil)
+/// ```
+///
+/// ```gleam
+/// > replace_error(Ok(1), Nil)
+/// Ok(1)
+/// ```
+///
 pub fn replace_error(result: Result(a, e1), error: e2) -> Result(a, e2) {
-  result
-  |> map_error(fn(_) { error })
+  case result {
+    Ok(x) -> Ok(x)
+    Error(_) -> Error(error)
+  }
 }
 
 /// Given a list of results, returns only the values inside `Ok`.
diff --git a/test/gleam/result_test.gleam b/test/gleam/result_test.gleam
index a2bd6ff..c34c7ed 100644
--- a/test/gleam/result_test.gleam
+++ b/test/gleam/result_test.gleam
@@ -163,6 +163,24 @@ pub fn replace_error_test() {
   |> should.equal(Error("Invalid"))
 }
 
+pub fn replace_error_with_ok_test() {
+  Ok(Nil)
+  |> result.replace_error("Invalid")
+  |> should.equal(Ok(Nil))
+}
+
+pub fn replace_test() {
+  Ok(Nil)
+  |> result.replace("OK")
+  |> should.equal(Ok("OK"))
+}
+
+pub fn replace_with_ok_test() {
+  Error(Nil)
+  |> result.replace("Invalid")
+  |> should.equal(Error(Nil))
+}
+
 pub fn values_test() {
   result.values([Ok(1), Error(""), Ok(3)])
   |> should.equal([1, 3])