X-Git-Url: http://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2FCardinal.hs;h=3bff38f206c5983cb29ac9f80ef99275f6a88e4c;hb=c954154b379c5bd444d527298c33142fb150711b;hp=42b1260bb13f72f530bd725fd89943da1c1d004f;hpb=084d6e31ba1eda1e7c206ff8ff23e8567e2339ce;p=spline3.git

diff --git a/src/Cardinal.hs b/src/Cardinal.hs
index 42b1260..3bff38f 100644
--- a/src/Cardinal.hs
+++ b/src/Cardinal.hs
@@ -1,12 +1,14 @@
 -- | The Cardinal module contains the Cardinal data type, representing
---   a cardinal direction (one of the 27 directions surrounding the
---   center of a cube. In addition to those 27 directions, we also
+--   a cardinal direction (one of the 26 directions surrounding the
+--   center of a cube. In addition to those 26 directions, we also
 --   include the interior point and a number of composite types that
 --   allow us to perform arithmetic on directions.
 module Cardinal
 where
 
+import Control.Monad (liftM, liftM2)
 import Prelude hiding (LT)
+import Test.QuickCheck (Arbitrary(..), oneof)
 
 data Cardinal = F   -- ^ Front
               | B   -- ^ Back
@@ -46,7 +48,7 @@ data Cardinal = F   -- ^ Front
                 deriving (Show, Eq)
 
 
--- | By making Cardinal an instance of Num, we gain the ability to
+-- | By making Cardinal an instance of 'Num', we gain the ability to
 --   add, subtract, and multiply directions. The results of these
 --   operations are never actually calculated; the types just keep
 --   track of which operations were performed in which order.
@@ -54,20 +56,60 @@ instance Num Cardinal where
     x + y = Sum x y
     x - y = Difference x y
     x * y = Product x y
-    negate x = Product (Scalar (-1)) x
+    negate = Product (Scalar (-1))
     abs x = x
     signum x = x
     fromInteger x = Scalar (fromIntegral x)
 
 
--- | Like the Num instance, the Fractional instance allows us to
+-- | Like the Num instance, the 'Fractional' instance allows us to
 --   take quotients of directions.
 instance Fractional Cardinal where
     x / y   = Quotient x y
-    recip x = Quotient (Scalar 1) x
+    recip = Quotient (Scalar 1)
     fromRational x = Scalar (fromRational x)
 
 
+
+instance Arbitrary Cardinal where
+    arbitrary = oneof [f,b,l,r,d,t,fl,fr,fd,ft,bl,br,bd,bt,ld,lt,
+                       rd,rt,fld,flt,frd,frt,bld,blt,brd,brt,i,
+                       scalar,csum,cdiff,cprod,cquot]
+        where
+          f = return F
+          b = return B
+          l = return L
+          r = return R
+          d = return D
+          t = return T
+          fl = return FL
+          fr = return FR
+          fd = return FD
+          ft = return FT
+          bl = return BL
+          br = return BR
+          bd = return BD
+          bt = return BT
+          ld = return LD
+          lt = return LT
+          rd = return RD
+          rt = return RT
+          fld = return FLD
+          flt = return FLT
+          frd = return FRD
+          frt = return FRT
+          bld = return BLD
+          blt = return BLT
+          brd = return BRD
+          brt = return BRT
+          i = return I
+          scalar = liftM Scalar arbitrary
+          csum = liftM2 Sum arbitrary arbitrary
+          cdiff = liftM2 Difference arbitrary arbitrary
+          cprod = liftM2 Product arbitrary arbitrary
+          cquot = liftM2 Quotient arbitrary arbitrary
+
+
 -- | Rotate a cardinal direction counter-clockwise about the x-axis.
 ccwx :: Cardinal -> Cardinal
 ccwx F = F
@@ -150,32 +192,32 @@ cwy = ccwy . ccwy . ccwy
 
 -- | Rotate a cardinal direction counter-clockwise about the z-axis.
 ccwz :: Cardinal -> Cardinal
-ccwz F = L
-ccwz B = R
-ccwz L = B
-ccwz R = F
+ccwz F = R
+ccwz B = L
+ccwz L = F
+ccwz R = B
 ccwz D = D
 ccwz T = T
-ccwz FL = BL
-ccwz FR = FL
-ccwz FD = LD
-ccwz FT = LT
-ccwz BL = BR
-ccwz BR = FR
-ccwz BD = RD
-ccwz BT = RT
-ccwz LD = BD
-ccwz LT = BT
-ccwz RD = FD
-ccwz RT = FT
-ccwz FLD = BLD
-ccwz FLT = BLT
-ccwz FRD = FLD
-ccwz FRT = FLT
-ccwz BLD = BRD
-ccwz BLT = BRT
-ccwz BRD = FRD
-ccwz BRT = FRT
+ccwz FL = FR
+ccwz FR = BR
+ccwz FD = RD
+ccwz FT = RT
+ccwz BL = FL
+ccwz BR = BL
+ccwz BD = LD
+ccwz BT = LT
+ccwz LD = FD
+ccwz LT = FT
+ccwz RD = BD
+ccwz RT = BT
+ccwz FLD = FRD
+ccwz FLT = FRT
+ccwz FRD = BRD
+ccwz FRT = BRT
+ccwz BLD = FLD
+ccwz BLT = FLT
+ccwz BRD = BLD
+ccwz BRT = BLT
 ccwz I = I
 ccwz (Scalar s) = (Scalar s)
 ccwz (Sum c0 c1) = Sum (ccwz c0) (ccwz c1)