string.to_option

3 files changed, 34 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e52fce4..a04e070 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,7 @@
   JavaScript.
 - The `dynamic` module functions now return structured error values instead of a
   string error description.
+- The `string` module gains the `to_option` function.
 
 ## v0.16.0 - 2021-06-17
 
diff --git a/src/gleam/string.gleam b/src/gleam/string.gleam
index 545d1e4..3f0ebe5 100644
--- a/src/gleam/string.gleam
+++ b/src/gleam/string.gleam
@@ -6,6 +6,7 @@ import gleam/iterator.{Iterator}
 import gleam/list
 import gleam/order
 import gleam/result
+import gleam/option.{None, Option, Some}
 
 if erlang {
   import gleam/dynamic.{Dynamic}
@@ -664,3 +665,24 @@ pub fn utf_codepoint(value: Int) -> Result(UtfCodepoint, Nil) {
     i -> Ok(unsafe_int_to_utf_codepoint(i))
   }
 }
+
+/// Convert a string into an optional string where an empty string becomes `None`.
+///
+/// ## Examples
+///
+/// ```gleam
+/// > to_option("")
+/// None
+/// ```
+///
+/// ```gleam
+/// > to_option("")
+/// None
+/// ```
+///
+pub fn to_option(s: String) -> Option(String) {
+  case s {
+    "" -> None
+    _ -> Some(s)
+  }
+}
diff --git a/test/gleam/string_test.gleam b/test/gleam/string_test.gleam
index 3612dbb..d3a8496 100644
--- a/test/gleam/string_test.gleam
+++ b/test/gleam/string_test.gleam
@@ -1,6 +1,7 @@
 import gleam/string
 import gleam/should
 import gleam/order
+import gleam/option.{None, Some}
 import gleam/io
 import gleam/bit_string
 
@@ -355,3 +356,13 @@ pub fn bit_string_utf_codepoint_test() {
   assert Ok(snake) = string.utf_codepoint(128013)
   should.equal(<<snake:utf8_codepoint>>, <<"🐍":utf8>>)
 }
+
+pub fn to_option_test() {
+  ""
+  |> string.to_option
+  |> should.equal(None)
+
+  "ok"
+  |> string.to_option
+  |> should.equal(Some("ok"))
+}