overview.hs helps generate OVERVIEW

overview.hs

@@ -0,0 +1,33 @@
+-- overview.hs - update an OVERVIEW file
+--
+-- OVERVIEW begins with a manually updated list of modules; below that we
+-- generate a list of filename, function, type entries. Useful for getting
+-- the big picture and refactoring.
+
+import System
+import System.Process
+import IO
+import Data.List
+import Text.Printf
+
+main = do
+  old <- readFile "OVERVIEW"
+  let preamble = takeWhile ((> 0) . length) $ lines old
+  putStr $ unlines preamble
+  let modules = concat $ map ((++ ".hs ") . dropWhile (== ' ')) preamble
+  let grep = "grep -H '^\\w[^=]*::' " ++ modules
+  (inp, out, err, pid) <- runInteractiveCommand grep
+  grepoutput <- hGetContents out
+  let groups = groupBy (\a b -> samefile a b) $ lines grepoutput
+  sequence $ map printgroup groups
+  putStr "\n"
+
+printgroup ls = do putStr "\n"; sequence $ map printline ls
+
+printline l = 
+    putStrLn $ printf "%-22s %-40s %s" (file++":") code typedecl
+    where
+      (file, rest) = break (== ':') l
+      (code, typedecl) = break (== ':') $ tail rest
+
+samefile a b = ((takeWhile (/= ':') a) ++ ":") `isPrefixOf` b