prevent some cases of non-scalar repeat

src/algorithm/loops.rs

@@ -48,6 +48,15 @@ pub fn repeat(env: &mut Uiua) -> UiuaResult {
  } else {
  // Array
  let sig = f.signature();
+ if sig.args != sig.outputs {
+ return Err(env.error(format!(
+ "{} with a non-scalar repetition count \
+ must use a function with the same number \
+ of arguments and outputs, but its signature \
+ is {sig}",
+ Primitive::Repeat.format()
+ )));
+ }
  // Collect arguments
  let mut args = Vec::with_capacity(sig.args + 1);
  let new_shape = n.shape().clone();

todo.md

@@ -4,7 +4,6 @@
  - Stack-source locality tutorial
  - Axis swizzles?
  - Rewrite .uasm format
- - Macro args doc comments
  - Fix pad cursor jumping with end-of-line comments
  - Unicode literals
  - Plots