[ #7 ] Found the problem: it's trying to check the signature of `leve…

…l0`, and because it fallbacks to `check(..., Type(0))` which causes problem.

I need to implement a more formal universe checker

samples/basics/univese.out

@@ -0,0 +1,2 @@
+Parse successful.
+Type-Check successful.

src/check/decl.rs

@@ -96,7 +96,6 @@ pub fn check_simple_declaration(
     check_type(index, tcs_borrow!(tcs), signature.clone())
         .map_err(|err| try_locate!(err, pattern))?;
     let signature = signature.eval(tcs.context());
-    println!("Signature of {} is: {}", pattern, signature);
     check(index, tcs_borrow!(tcs), body.clone(), signature.clone())
         .map_err(|err| try_locate!(err, pattern))?;
     let TCS { gamma, context } = tcs;