Rewrite everything to use Maybe instead of None constructors.

[hath.git] / src / Maskable.hs

diff --git a/src/Maskable.hs b/src/Maskable.hs
index 1441c07a6757b8ae3d80f781c52d8fb6fb5ea01d..d05ff6ffbaf63b9695206f596bdd1bc154afc1e4 100644 (file)
--- a/src/Maskable.hs
+++ b/src/Maskable.hs
@@ -1,17 +1,22 @@
 module Maskable where
 
+import Bit
 import Maskbits
 
--- Any string of bits should be maskable by some number of netmask
--- bits. The convention of the Maskable typeclass follows CIDR
--- notation, where the number of mask bits (the number after the
--- slash) denotes how many bits are reserved for the network.
+-- | Any string of bits should be maskable by some number of netmask
+--   bits. The convention of the Maskable typeclass follows CIDR
+--   notation, where the number of mask bits (the number after the
+--   slash) denotes how many bits are reserved for the network.
+--
+--   So, a mask of 32 applied to an address of 127.0.0.1 will again
+--   return 127.0.0.1. Likewise, 31 mask bits applied to 127.0.0.1
+--   should return 127.0.0.0, since 127.0.0.1/31 matches both
+--   127.0.0.0 and 127.0.0.1. In this case, the final '0' or '1' is
+--   the host part of the address. The '127.0.0' is thus the network
+--   part.
+--
+--   The Bit argument allows us to specify whether the host bits
+--   should be replaced with either Zero or One.
 --
--- So, a mask of 32 applied to an address of 127.0.0.1 will again
--- return 127.0.0.1. Likewise, 31 mask bits applied to 127.0.0.1
--- should return 127.0.0.0, since 127.0.0.1/31 matches both 127.0.0.0
--- and 127.0.0.1. In this case, the final '0' or '1' is the host
--- part of the address. The '127.0.0' is thus the network part.
 class Maskable a where
-    apply_mask :: a -> Maskbits -> a
-
+    apply_mask :: a -> Maskbits -> Bit -> a