+\begin{code}
+eqExpr :: InScopeSet -> CoreExpr -> CoreExpr -> Bool
+-- Compares for equality, modulo alpha
+eqExpr in_scope e1 e2
+ = go (mkRnEnv2 in_scope) e1 e2
+ where
+ go _ (Lit lit1) (Lit lit2) = lit1 == lit2
+ go env (Type t1) (Type t2) = coreEqType2 env t1 t2
+ go env (Var v1) (Var v2) = rnOccL env v1 == rnOccR env v2
+ go env (Cast e1 t1) (Cast e2 t2) = go env e1 e2 && coreEqCoercion2 env t1 t2
+ go env (App f1 a1) (App f2 a2) = go env f1 f2 && go env a1 a2
+
+ go env (Lam b1 e1) (Lam b2 e2)
+ = coreEqType2 env (varType b1) (varType b2) -- Will return False for Id/TyVar combination
+ && go (rnBndr2 env b1 b2) e1 e2
+
+ go env (Case e1 b1 _ a1) (Case e2 b2 _ a2)
+ = go env e1 e2
+ && coreEqType2 env (idType b1) (idType b2)
+ && all2 (go_alt (rnBndr2 env b1 b2)) a1 a2
+
+ go env (Let (NonRec b1 r1) e1) (Let (NonRec b2 r2) e2)
+ = go env r1 r2 -- No need to check binder types, since RHSs match
+ && go (rnBndr2 env b1 b2) e1 e2
+
+ go env (Let (Rec p1) e1) (Let (Rec p2) e2)
+ | equalLength p1 p2
+ = all2 (go env') rs1 rs2 && go env' e1 e2
+ where
+ (bs1,rs1) = unzip p1
+ (bs2,rs2) = unzip p2
+ env' = rnBndrs2 env bs1 bs2