[project @ 1997-07-31 00:05:10 by sof]

[ghc-hetmet.git] / ghc / compiler / tests / typecheck / should_fail / Digraph.hs

diff --git a/ghc/compiler/tests/typecheck/should_fail/Digraph.hs b/ghc/compiler/tests/typecheck/should_fail/Digraph.hs
deleted file mode 100644 (file)
index a52d489..0000000
--- a/ghc/compiler/tests/typecheck/should_fail/Digraph.hs
+++ /dev/null
@@ -1,56 +0,0 @@
---!!! trying to have a polymorphic type sig where inappropriate
---
-module Digraph where
-
-data MaybeErr val err = Succeeded val | Failed err deriving ()
-
-type Edge  vertex = (vertex, vertex)
-type Cycle vertex = [vertex]
-
-stronglyConnComp :: Eq vertex => [Edge vertex] -> [vertex] -> [[vertex]]
-
-stronglyConnComp es vs
-  = snd (span_tree (new_range reversed_edges)
-                   ([],[])
-                   ( snd (dfs (new_range es) ([],[]) vs) )
-        )
- where
-   -- *********** the offending type signature **************
-   reversed_edges :: Eq v => [Edge v]
-   reversed_edges = map swap es
-
-   -- WRONGOLA: swap :: Eq v => Edge v -> Edge v
-   swap (x,y) = (y, x)
-
-   -- WRONGOLA?: new_range :: Eq v => [Edge v] -> v -> [v]
-
-   new_range    []       w = []
-   new_range ((x,y):xys) w
-       = if x==w
-         then (y : (new_range xys w))
-         else (new_range xys w)
-
-   {- WRONGOLA?:
-   span_tree :: Eq v => (v -> [v])
-                     -> ([v], [[v]])
-                     -> [v]
-                     -> ([v], [[v]])
-    -}
-
-   span_tree r (vs,ns) []   = (vs,ns)
-   span_tree r (vs,ns) (x:xs)
-       | x `elem` vs = span_tree r (vs,ns) xs
-       | otherwise = span_tree r (vs',(x:ns'):ns) xs
-         where
-           (vs',ns') = dfs r (x:vs,[]) (r x)
-
-dfs :: Eq v => (v -> [v])
-            -> ([v], [v])
-            -> [v]
-            -> ([v], [v])
-
-dfs r (vs,ns)   []   = (vs,ns)
-dfs r (vs,ns) (x:xs) | x `elem` vs = dfs r (vs,ns) xs
-                     | otherwise = dfs r (vs',(x:ns')++ns) xs
-                                   where
-                                     (vs',ns') = dfs r (x:vs,[]) (r x)