From 4e987026148fe65c323afbc93cd560c07bf06b3f Mon Sep 17 00:00:00 2001
From: Yale AI Dept <ai@nebula.cs.yale.edu>
Date: Wed, 14 Jul 1993 13:08:00 -0500
Subject: Import to github.

---
 progs/lib/hbc/Hash.hs | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 progs/lib/hbc/Hash.hs

(limited to 'progs/lib/hbc/Hash.hs')

diff --git a/progs/lib/hbc/Hash.hs b/progs/lib/hbc/Hash.hs
new file mode 100644
index 0000000..1f14c6f
--- /dev/null
+++ b/progs/lib/hbc/Hash.hs
@@ -0,0 +1,79 @@
+module Hash where
+--
+-- Hash a value.  Hashing produces an Int of
+-- unspecified range.
+--
+
+class Hashable a where
+    hash :: a -> Int
+
+instance Hashable Char where
+    hash x = ord x
+
+instance Hashable Int where
+    hash x = x
+
+instance Hashable Integer where
+    hash x = fromInteger x
+
+instance Hashable Float where
+    hash x = truncate x
+
+instance Hashable Double where
+    hash x = truncate x
+
+instance Hashable Bin where
+    hash x = 0
+
+{-instance Hashable File where
+    hash x = 0 -}
+
+instance Hashable () where
+    hash x = 0
+
+instance Hashable (a -> b) where
+    hash x = 0
+
+instance Hashable a => Hashable [a] where
+    hash x = sum (map hash x)
+
+instance (Hashable a, Hashable b) => Hashable (a,b) where
+    hash (a,b) = hash a + 3 * hash b
+
+instance (Hashable a, Hashable b, Hashable c) => Hashable (a,b,c) where
+    hash (a,b,c) = hash a + 3 * hash b + 5 * hash c
+
+instance (Hashable a, Hashable b, Hashable c, Hashable d) => Hashable (a,b,c,d) where
+    hash (a,b,c,d) = hash a + 3 * hash b + 5 * hash c + 7 * hash d
+
+instance (Hashable a, Hashable b, Hashable c, Hashable d, Hashable e) => Hashable (a,b,c,d,e) where
+    hash (a,b,c,d,e) = hash a + hash b + hash c + hash d + hash e
+
+instance Hashable Bool where
+    hash False = 0
+    hash True = 1
+
+instance (Integral a, Hashable a) => Hashable (Ratio a) where
+    hash x = hash (denominator x) + hash (numerator x)
+
+instance (RealFloat a, Hashable a) => Hashable (Complex a) where
+    hash (x :+ y) = hash x + hash y
+
+instance (Hashable a, Hashable b) => Hashable (Assoc a b) where
+    hash (x := y) = hash x + hash y
+
+instance (Ix a) => Hashable (Array a b) where
+    hash x = 0 -- !!!
+
+instance Hashable Request where
+    hash x = 0 -- !!
+
+instance Hashable Response where
+    hash x = 0 -- !!
+
+instance Hashable IOError where
+    hash x = 0 -- !!
+
+hashToMax maxhash x =
+    let h = abs (hash x)
+    in  if h < 0 then 0 else h `rem` maxhash
-- 
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