Lam. Exp  ::= "\\" "(" Ident ":" Type ")" "->" Exp;
App. Exp1 ::= Exp1 Exp2;
Var. Exp2 ::= Ident;
Lit. Exp2 ::= Integer;
coercions Exp 2;

FunT. Type  ::= Type1 "->" Type;
ConT. Type1 ::= Ident;
coercions Type 1;