start implementing new recur modifier

Author: kaikalii

src/algorithm/mod.rs

@@ -31,6 +31,7 @@ pub mod media;
 mod monadic;
 pub mod path;
 pub mod pervade;
+pub mod recur;
 pub mod reduce;
 pub mod stencil;
 pub mod table;

src/algorithm/recur.rs

@@ -0,0 +1,5 @@
+use crate::{Uiua, UiuaResult};
+
+pub fn recur(env: &mut Uiua) -> UiuaResult {
+    Ok(())
+}