Clippy: Simplify Literal variant

The CMR value of this variant is never used. Maybe the design of the
humanb encoding changed and the Literal variant became useless?

src/human_encoding/parse/ast.rs

@@ -3,7 +3,6 @@
 //! Parsing
 
 use std::mem;
-use std::str::FromStr;
 use std::sync::Arc;
 
 use crate::human_encoding::{Error, ErrorSet, Position, WitnessOrHole};
@@ -61,7 +60,7 @@ pub enum ExprInner<J> {
 #[derive(Debug, PartialEq, Eq, Clone, Hash)]
 pub enum AstCmr<J> {
     Expr(Arc<Expression<J>>),
-    Literal(Cmr),
+    Literal,
 }
 
 /// A type, as represented in the AST
@@ -395,9 +394,7 @@ impl<J: Jet> Ast<J> {
         assert_eq!(lexemes.len(), 1);
         assert_eq!(lexemes[0].raw.len(), 65);
 
-        Ast::Cmr(AstCmr::Literal(
-            Cmr::from_str(&lexemes[0].raw[1..]).unwrap(),
-        ))
+        Ast::Cmr(AstCmr::Literal)
     }
 
     fn expect_arrow(&mut self) -> (Option<Type>, Option<Type>) {

src/human_encoding/parse/mod.rs

@@ -8,7 +8,6 @@ use crate::dag::{Dag, DagLike, InternalSharing};
 use crate::jet::Jet;
 use crate::node;
 use crate::types::Type;
-use crate::Cmr;
 use std::collections::HashMap;
 use std::mem;
 use std::sync::atomic::{AtomicUsize, Ordering};
@@ -139,7 +138,7 @@ struct ResolvedExpression<J: Jet> {
 
 enum ResolvedCmr<J: Jet> {
     Expr(Arc<ResolvedExpression<J>>),
-    Literal(Cmr),
+    Literal,
 }
 
 enum ResolvedInner<J: Jet> {
@@ -312,7 +311,7 @@ pub fn parse<J: Jet + 'static>(
                             right.in_degree.fetch_add(1, Ordering::SeqCst);
                             ResolvedCmr::Expr(right)
                         }
-                        ast::AstCmr::Literal(cmr) => ResolvedCmr::Literal(*cmr),
+                        ast::AstCmr::Literal => ResolvedCmr::Literal,
                     };
                     ResolvedInner::AssertL(left, right)
                 }
@@ -323,7 +322,7 @@ pub fn parse<J: Jet + 'static>(
                             left.in_degree.fetch_add(1, Ordering::SeqCst);
                             ResolvedCmr::Expr(left)
                         }
-                        ast::AstCmr::Literal(cmr) => ResolvedCmr::Literal(*cmr),
+                        ast::AstCmr::Literal => ResolvedCmr::Literal,
                     };
 
                     let right = inline_stack.pop().unwrap();
@@ -413,8 +412,8 @@ pub fn parse<J: Jet + 'static>(
                 | ResolvedInner::AssertR(ResolvedCmr::Expr(ref left), ref right) => {
                     Dag::Binary(left, right)
                 }
-                ResolvedInner::AssertL(ref child, ResolvedCmr::Literal(..))
-                | ResolvedInner::AssertR(ResolvedCmr::Literal(..), ref child) => Dag::Unary(child),
+                ResolvedInner::AssertL(ref child, ResolvedCmr::Literal)
+                | ResolvedInner::AssertR(ResolvedCmr::Literal, ref child) => Dag::Unary(child),
                 ResolvedInner::Inline(ref inner) => inner.as_dag().map(|node| node),
             }
         }