paExpr
   = pgAlts 
     [
        paCaseExpr, 
        paLetExpr, 
        paLamExpr,
        paIfExpr,
        paUnaryMinusExpr,
        hsDoExpr []
     ]
paExpr
   = pgAlts 
     [
        paCaseExpr, 
        paLetExpr, 
        paLamExpr,
        paIfExpr,
        paUnaryMinusExpr,
        hsDoExpr []
     ]
paExpr
   = pgAlts 
     [
        paCaseExpr, 
        paLetExpr, 
        paLamExpr,
        paIfExpr,
        paUnaryMinusExpr,
        hsDoExpr []
     ]