Consistent pretty-printing for open and closed type families

[jstolarek]

Currently pretty printing equations of open and closed type family equations is inconsistent:

   Calling type family ‘Id’ is not allowed in injective type family equation:
      IdProxy a -- Defined at T6018fail.hs:27:15

    Calling type family ‘IdClosed’ is not allowed in injective type family equation:
      IdProxyClosed a = IdClosed a

I want two fixes:

• for open type families print the RHS
• for closed type families print location

[jstolarek]

Suppose I say:

type family F a b (c :: k) = r | r -> a b

type family Fa a b (c :: k) = r | r -> a b c where
    Fa a b c = [F a b c]

I get:

Type family equation violates injectivity annotation.
Injective type variable ‘c’ does not appear on injective position.
Injective kind variable ‘k’ is not inferable from the RHS type variables.
In the RHS of type family equation:
forall (k :: BOX) a b (c :: k). Fa a b c = [F a b c]
In the equations for closed type family ‘Fa’
In the type family declaration for ‘Fa’

The quantified type family equation is not indented, unlike equations without forall. Thus I want a third fix:

• indent equations preceded by forall.

[jstolarek]

After converting Fa to an open type family the equation is printed without forall quantifier - another inconsistency.

[jstolarek]

After changes in 00680ef86417907960e87f28c58b0024db2ffe10 there is no more inconsistency because makeInjectivityErrors now works for CoAxBranch (previously it was polymorphic to work with FamInst as well). The difference in pretty printing is exactly the difference between pprinting CoAxBranch and FamInst.