xpr :: LCParsec StringSF
sfexpr = label "System-F expression" $
          exprsequence (typevar <$> variable
                    <|> typeconst <$> constant
                    <|> paren sfexpr)

s
sfexpr :: LCParsec StringSF
sfexpr = label "System-F expression" $
          exprsequence (typevar <$> variable
                    <|> typeconst <$> constant
                    <|> paren sfexpr)
sfexpr = label "System-F expression" $
          exprsequence (typevar <$> variable
                    <|> typeconst <$> constant
                    <|> paren sfexpr)