From a067356625105f50978443d3b0a0a5d8f6391184 Mon Sep 17 00:00:00 2001 From: Mart Lubbers Date: Fri, 24 Apr 2015 14:35:17 +0200 Subject: rare shit --- fp2/week2/mart/oldold/old/StdIOMonad.icl | 93 ++++++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+) create mode 100644 fp2/week2/mart/oldold/old/StdIOMonad.icl (limited to 'fp2/week2/mart/oldold/old/StdIOMonad.icl') diff --git a/fp2/week2/mart/oldold/old/StdIOMonad.icl b/fp2/week2/mart/oldold/old/StdIOMonad.icl new file mode 100644 index 0000000..0338a44 --- /dev/null +++ b/fp2/week2/mart/oldold/old/StdIOMonad.icl @@ -0,0 +1,93 @@ +implementation module StdIOMonad + +//Deze module verpakt StdFile in een monadische jas + +import StdFile +import StdMonad +import StdMaybeMonad + + +:: IO a = IO (*World Filehandle -> *(a, *World, Filehandle)) +:: Void = Void +:: Filemode = Lees | Schrijf +:: Filenaam :== String +:: *Filehandle = None | FH *(Bool, Filemode, *File) + +toInt :: Filemode -> Int +toInt Lees = FReadText +toInt Schrijf = FWriteText + +Start world = read + +////voer monadische I/O actie uit op de wereld: +//doIO :: (IO a) *World -> *(a,*World) +//doIO (IO f) world = f (world, Closed) + +// IO is een monad: +instance return IO where + return x = IO (\w fh = (x, w, fh)) +//instance >>= IO where +// (>>=) (IO f) g = IO(\w = let (a, w1) = f w in doIO (g a) w1) + +//lees regel van de console: +read:: IO String +read = IO (\w fh -> ("", w, fh)) + +/*//schrijf regel naar de console: +write:: String -> IO Void +write s = IO (\w = (Void, write` s w)) + where + write`:: String *World -> *World + write` s world + # (io, world) = stdio world + # io = fwrites s world + # (_, world) = fclose io + = world + +//open de file met gegeven filenaam en mode: +open:: Filenaam Filemode -> IO (Maybe Filehandle) +open s m = IO (\w = let (f1, w1) = openfh` s m w in (f1, (w1, f1))) + where + openfh`:: Filenaam Filemode *World -> (Maybe Filehandle, *World) + openfh` s m world + # (ok, file, world) = fopen s (toInt m) world + | ok = (Just (Open (m, file)), world) + | otherwise = (Nothing, world) + +//sluit de file met gegeven filenaam: +close:: Filehandle -> IO Bool +close fh = IO (\w = let (b1, w1) = close` fh w in (b1, (w1, Closed))) + where + close`:: Filehandle *World -> (Bool, *World) + close` Closed world = (False, world) + close` (Open (_, file)) world = fclose file world + +//bepaal of het lezen van de file klaar is: +eof:: Filehandle -> IO Bool +eof fh = IO (\w = let (b1, w1) = eof` fh w in (b1, (w1, Closed))) + where + eof`:: Filehandle *World -> (Bool, *World) + eof` Closed world = (world, False) + eaf`(Open (_, file)) world = fclose file + +//lees een regel van een file: +readline:: Filehandle -> IO (Maybe String) +readline fh = IO (\w = let r1 = readline` fh w in r1) + where + readline`:: Filehandle *World -> (Maybe String, (*World, Filehandle)) + readline` Closed world = (world, Nothing) + readline` (Open (Schrijf, _)) world = (world, Nothing) + readline` (Open (Lees, file)) world + # (line, file) = sfreadline file + = (Just line, (world, Open (Lees, file))) + +//schrijf een regel naar een file: +writeline:: String Filehandle -> IO Bool +writeline s fh = IO (\w = let r1 = writeline` s fh w in r1) + where + writeline`:: String Filehandle *World -> (Bool, (*World, Filehandle)) + writeline` line Closed world = (False, (world, Closed)) + writeline` line (Open (Lees, file)) world = (False, (world, (Open (Lees, file)))) + writeline` line (Open (Schrijf, file)) world + # file = fwrites line file + = (True, (world, file))*/ -- cgit v1.2.3