| BSLASH SYMBOL COLON LPAREN typ RPAREN ARROW exp (ELam (SYMBOL, SOME typ, exp),
(BSLASHleft, expright))
| BSLASH SYMBOL ARROW exp (ELam (SYMBOL, NONE, exp), (BSLASHleft, expright))
| BSLASH SYMBOL COLON LPAREN typ RPAREN ARROW exp (ELam (SYMBOL, SOME typ, exp),
(BSLASHleft, expright))
| BSLASH SYMBOL ARROW exp (ELam (SYMBOL, NONE, exp), (BSLASHleft, expright))