Applying data type with wrong number of abstract refinement params could give better errors

[csgordon]

module Arity where

{-@ data T a <p :: a -> Prop, q :: a -> Prop > = MkT (t_x :: a) @-}
data T a = MkT a

-- error spec 1
{- f :: forall <p :: a -> Prop, q :: a -> Prop>. T <p> a -> a @-}
-- error spec 2
{- f :: forall <p :: a -> Prop, q :: a -> Prop>. T <p, q, {\ y -> (true)}> a -> a @-}
f :: T a -> a
f (MkT x) = x

The first spec, if used, produces:

LiquidHaskell Copyright 2009-14 Regents of the University of California. All Rights Reserved.

liquid: 
**** ERROR *********************************************************************
**** ERROR *********************************************************************
**** ERROR *********************************************************************
safeZipWith called on non-eq-sized lists (nxs = 2, nys = 1) : appRefts: Arity.T
**** ERROR *********************************************************************
**** ERROR *********************************************************************
**** ERROR *********************************************************************

This at least contains enough information to figure out it's a misapplication of Arity.T, but requires manually inspecting everywhere you wrote a LH spec using T.

The second spec's error is less helpful:

LiquidHaskell Copyright 2009-14 Regents of the University of California. All Rights Reserved.

liquid: 
**** ERROR *********************************************************************
**** ERROR *********************************************************************
**** ERROR *********************************************************************
YUCKER
**** ERROR *********************************************************************
**** ERROR *********************************************************************
**** ERROR *********************************************************************

This one also requires looking at all uses of T in LH specs, but I figured this out purely by luck. Curiously, if you replace the lambda in that spec with another use of p or q, the file type-checks despite the bad type application.