tcfail016.hs:9: Couldn't match the type
		    `PrelTup.(,) a{-aX1-}' against `Expr'
    Expected: `Expr a{-aWV-}'
    Inferred: `AnnExpr a{-aX1-}'
    In the first argument of `g', namely
	`e1'
    In the first argument of `PrelBase.++', namely
	(`g' `e1')
    In an equation for function `g':
	`g (App e1 e2)
		   =   (g   e1) PrelBase.++ (g   e2)'


Compilation had errors