paUnaryMinusExpr
   = pgThen2
        (\minus (_, aexpr, _) -> 
             ExprApp (ExprApp (ExprVar "-") (ExprLiteral (LiteralInt 0))) aexpr)
        paMinus
        paAExpr
paUnaryMinusExpr
   = pgThen2
        (\minus (_, aexpr, _) -> 
             ExprApp (ExprApp (ExprVar "-") (ExprLiteral (LiteralInt 0))) aexpr)
        paMinus
        paAExpr
paUnaryMinusExpr
   = pgThen2
        (\minus (_, aexpr, _) -> 
             ExprApp (ExprApp (ExprVar "-") (ExprLiteral (LiteralInt 0))) aexpr)
        paMinus
        paAExpr