Lower- and uppercase string conversion functions

src/library/mod.rs

@@ -63,6 +63,8 @@ pub fn new() -> Scope {
     std.def_func("rgb", rgb);
     std.def_func("min", min);
     std.def_func("max", max);
+    std.def_func("lower", lower);
+    std.def_func("upper", upper);
 
     // Colors.
     std.def_const("white", RgbaColor::WHITE);

src/library/utility.rs

@@ -75,3 +75,13 @@ fn minmax(args: &mut Arguments, goal: Ordering) -> TypResult<Value> {
     }
     Ok(extremum)
 }
+
+/// `lower`: Convert a string to lowercase.
+pub fn lower(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
+    Ok(args.expect::<Str>("string")?.to_lowercase().into())
+}
+
+/// `upper`: Convert a string to uppercase.
+pub fn upper(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
+    Ok(args.expect::<Str>("string")?.to_uppercase().into())
+}

tests/typ/utility/strings.typ

@@ -0,0 +1,8 @@
+// Test string functions.
+// Ref: false
+
+---
+#let memes = "ArE mEmEs gReAt?";
+#test(lower(memes), "are memes great?")
+#test(upper(memes), "ARE MEMES GREAT?")
+#test(upper("Ελλάδα"), "ΕΛΛΆΔΑ")