ghc/tests/typecheck/should_fail/Digraph.stderr

   1
   2 Digraph.hs:19: A type signature is more polymorphic than the inferred type
   3                    Some type variables in the inferred type can't be forall'd, namely:
   4                    `taXO'
   5                    Possible cause: the RHS mentions something subject to the monomorphism restriction
   6     When checking signature for `reversed_edges'
   7     In an equation for function `stronglyConnComp':
   8         `stronglyConnComp es vs
   9                           = PrelTup.snd (span_tree (new_range reversed_edges)
  10                                                    (PrelBase.[], (PrelBase.[]))
  11                                                    (PrelTup.snd (dfs (new_range es)
  12                                                                      (PrelBase.[], (PrelBase.[]))
  13                                                                      vs)))
  14                           where
  15                               span_tree r (vs, ns) PrelBase.[] = (vs, (ns))
  16                               span_tree r (vs, ns) (x PrelBase.: xs)
  17                                         | [x PrelList.elem vs] = span_tree r (vs, (ns)) xs
  18                                         | [PrelBase.otherwise]
  19                                         = span_tree r (vs', ((x PrelBase.: ns') PrelBase.: ns)) xs
  20                                         where
  21                                             (vs', ns')
  22                                                 = dfs r (x PrelBase.: vs, (PrelBase.[])) (r x)
  23                               new_range PrelBase.[] w = PrelBase.[]
  24                               new_range ((x, y) PrelBase.: xys) w
  25                                         = if x PrelBase.== w then
  26                                               (y PrelBase.: (new_range xys w))
  27                                           else
  28                                               (new_range xys w)
  29                               swap (x, y) = (y, (x))
  30                               reversed_edges :: _forall_ [v] (PrelBase.Eq v) => [Edge v]
  31                               reversed_edges = PrelBase.map swap es'
  32
  33
  34 Compilation had errors