Added more helpers methods on Option

Author: Wilfred

CHANGELOG.md

@@ -13,6 +13,8 @@ Added `+=` and `-=` operators.
 
 Added `assert()` and removed `should_equal()`.
 
+Added `Option::is_some()` and `Option::is_none()`.
+
 Removed `List::for_each` (use `for x in y` loops instead).
 
 ## Checks

src/prelude.gdn

@@ -32,6 +32,22 @@ enum Option<T> {
     None,
 }
 
+/// Return True if this value is `Some`.
+fun<T> (this: Option<T>) is_some(): Bool {
+    match this {
+        Some(_) => True,
+        None => False,
+    }
+}
+
+/// Return True if this value is `None`.
+fun<T> (this: Option<T>) is_none(): Bool {
+    match this {
+        Some(_) => False,
+        None => True,
+    }
+}
+
 // `Result` represents a value that succeeded, with `Ok(...)`, or
 // failed, with `Err(...)`.
 enum Result<T, E> {

src/test_files/go_to_def/method_name.gdn

@@ -5,5 +5,5 @@ fun file_name(path: String) {
 
 // args: definition-position
 // expected stdout:
-// {"start_offset":7804,"end_offset":7809,"line_number":350,"end_line_number":350,"path":"prelude.gdn"}
+// {"start_offset":8120,"end_offset":8125,"line_number":366,"end_line_number":366,"path":"prelude.gdn"}