B

Task/Bitmap-Read-a-PPM-file/Haskell/bitmap-read-a-ppm-file-1.hs

@@ -0,0 +1,12 @@
+import Bitmap
+import Bitmap.RGB
+import Bitmap.Gray
+import Bitmap.Netpbm
+
+import Control.Monad
+import Control.Monad.ST
+
+main =
+    (readNetpbm "original.ppm" :: IO (Image RealWorld RGB)) >>=
+    stToIO . toGrayImage >>=
+    writeNetpbm "new.pgm"

Task/Bitmap-Read-a-PPM-file/Haskell/bitmap-read-a-ppm-file-2.hs

@@ -0,0 +1,4 @@
+main =
+    (readNetpbm "original.ppm" :: IO (Image RealWorld RGB)) >>=
+    stToIO . (toRGBImage <=< toGrayImage) >>=
+    writeNetpbm "new.ppm"