Compilation with ghc 7.10.1 fails

[alpako]

Compilation with ghc-7.10.1 suggests to use the FlexibleContexts language extension.

src/Data/Union/ST.hs:131:13:
    Non type-variable argument
      in the constraint: MArray (STArray s) l m
    (Use FlexibleContexts to permit this)
    When checking that ‘cont’ has the inferred type
      cont :: forall (m :: * -> *).
              MArray (STArray s) l m =>
              Int -> l -> Int -> l -> m (Maybe a)
    In the expression:
      do { ra <- readArray (rank u) a';
           rb <- readArray (rank u) b';
           let cont x vx y vy = ...;
           case ra `compare` rb of {
             LT -> do { ... }
             GT -> do { ... }
             EQ -> do { ... } } }
    In a stmt of a 'do' block:
      if a' == b' then
          return Nothing
      else
          do { ra <- readArray (rank u) a';
               rb <- readArray (rank u) b';
               let cont x vx y vy = ...;
               .... }

[int-e]

We just released a fixed version on hackage.