ghc/tests/typecheck/should_fail/Digraph.stderr

   1
   2 Digraph.hs:19: A type signature is more polymorphic than the inferred type
   3                    Can't for-all the type variable(s) `taW8'
   4                    in the inferred type `[Edge taW8]'
   5     When checking signature for `reversed_edges'
   6     In an equation for function `stronglyConnComp':
   7         `stronglyConnComp es vs
   8                           = PrelTup.snd (span_tree (new_range reversed_edges)
   9                                                    (PrelBase.[], (PrelBase.[]))
  10                                                    (PrelTup.snd (dfs (new_range es)
  11                                                                      (PrelBase.[], (PrelBase.[]))
  12                                                                      vs)))
  13                           where
  14                               span_tree r (vs, ns) PrelBase.[] = (vs, (ns))
  15                               span_tree r (vs, ns) (x PrelBase.: xs)
  16                                         | x PrelList.elem vs = span_tree r (vs, (ns)) xs
  17                                         | PrelBase.otherwise
  18                                         = span_tree r (vs', ((x PrelBase.: ns') PrelBase.: ns)) xs
  19                                         where
  20                                             (vs', ns')
  21                                                 = dfs r (x PrelBase.: vs, (PrelBase.[])) (r x)
  22                               new_range PrelBase.[] w = PrelBase.[]
  23                               new_range ((x, y) PrelBase.: xys) w
  24                                         = if x PrelBase.== w then
  25                                               (y PrelBase.: (new_range xys w))
  26                                           else
  27                                               (new_range xys w)
  28                               swap (x, y) = (y, (x))
  29                               reversed_edges :: _forall_ [v] (PrelBase.Eq v) => [Edge v]
  30                               reversed_edges = PrelBase.map swap es'
  31
  32 Compilation had errors