Liberal Coverage Condition Failure at Compilation

[yihming]

When compiling with GHC 8.4.3, a liberal coverage condition failure happened for "HasValue" typeclass instance declarations in "Imperative/Internals.hs", Line 86 and 88.

For the functional dependency "b -> r i", in each instance declaration, RHS types must appear in LHS. However, in "instance HasValue r (V TyVar r) i", variable "i" does not appear in "V TyVar r", and thus is not determined.

I don't know if this is due to a different version of GHC, as the project was written 6 years ago...