diff --git a/Chapter12.hs b/Chapter12.hs
--- a/Chapter12.hs
+++ b/Chapter12.hs
@@ -53,10 +53,11 @@
type RegExp = String -> Bool
-char :: Char -> RegExp
+epsilon :: RegExp
epsilon = (=="")
+char :: Char -> RegExp
char ch = (==[ch])
(|||) :: RegExp -> RegExp -> RegExp
@@ -64,27 +65,59 @@
e1 ||| e2 =
\x -> e1 x || e2 x
-(<*>) :: RegExp -> RegExp -> RegExp
+(<++>) :: RegExp -> RegExp -> RegExp
-e1 <*> e2 =
+e1 <++> e2 =
\x -> or [ e1 y && e2 z | (y,z) <- splits x ]
-(<**>) :: RegExp -> RegExp -> RegExp
+(<+++>) :: RegExp -> RegExp -> RegExp
-e1 <**> e2 =
+e1 <+++> e2 =
\x -> or [ e1 y && e2 z | (y,z) <- fsplits x ]
+splits :: [a] -> [([a], [a])]
+
splits xs = [splitAt n xs | n<-[0..len]]
where
len = length xs
star :: RegExp -> RegExp
-star p = epsilon ||| (p <**> star p)
--- epsilon ||| (p <*> star p)
+star p = epsilon ||| (p <+++> star p)
+-- epsilon ||| (p <++> star p)
-- is OK as long as p can't have epsilon match
-fsplits xs = tail (splits xs)
+fsplits :: [a] -> [([a], [a])]
+
+fsplits = tail . splits
+
+-- Regular expressions as data
+
+data RE =
+ Epsilon |
+ Chr Char |
+ Or RE RE |
+ Seq RE RE |
+ Star RE
+ deriving (Show,Eq)
+
+-- Interpreting REs as functions i.e. RegExps
+
+match :: RE -> RegExp
+match Epsilon = epsilon
+match (Chr c) = char c
+match (Or e f) = match e ||| match f
+match (Seq e f) = match e <++> match f
+match (Star e) = star (match e)
+
+-- Simplifying REs …
+
+simplify :: RE -> RE
+simplify (Seq Epsilon e) = e
+simplify (Seq e Epsilon) = e
+simplify (Star (Star e)) = Star e
+ -- can add more cases here …
+simplify x = x
--
-- Case studies: functions as data
diff --git a/Chapter19/ParseLib.hs b/Chapter19/ParseLib.hs
--- a/Chapter19/ParseLib.hs
+++ b/Chapter19/ParseLib.hs
@@ -123,8 +123,11 @@
instance Monad (SParse a) where
return x = SParse (succeed x)
- (SParse pr) >>= f
+ (SParse pr) >>= f
= SParse (\st -> concat [ sparse (f a) rest | (a,rest) <- pr st ])
+
+instance MonadFail (SParse a) where
+ fail s = SParse none
instance Applicative (SParse a) where
pure = return
diff --git a/Craft3e.cabal b/Craft3e.cabal
--- a/Craft3e.cabal
+++ b/Craft3e.cabal
@@ -1,6 +1,6 @@
name: Craft3e
-version: 0.2.0.2
+version: 0.2.0.3
license: MIT
license-file: LICENSE
copyright: (c) Addison Wesley
@@ -46,6 +46,7 @@
open-browser >= 0.1.0.0 && < 0.5.0.0
exposed-modules:
+
Chapter1
Chapter10
Chapter11
@@ -113,9 +114,6 @@
RandomGen
ServerState
TopLevelServe
-
- other-modules:
-
hs-source-dirs: . ./Calculator ./Chapter15 ./Chapter16 ./Chapter19 ./Simulation ./Chapter20
diff --git a/ParseLib.hs b/ParseLib.hs
--- a/ParseLib.hs
+++ b/ParseLib.hs
@@ -123,8 +123,11 @@
instance Monad (SParse a) where
return x = SParse (succeed x)
- (SParse pr) >>= f
+ (SParse pr) >>= f
= SParse (\st -> concat [ sparse (f a) rest | (a,rest) <- pr st ])
+
+instance MonadFail (SParse a) where
+ fail s = SParse none
instance Applicative (SParse a) where
pure = return
diff --git a/Pictures.hs b/Pictures.hs
--- a/Pictures.hs
+++ b/Pictures.hs
@@ -62,6 +62,7 @@
printPicture = putStr . concat . map (++"\n")
+render = printPicture
-- Transformations of pictures.
-- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -70,7 +71,7 @@
flipV :: Picture -> Picture
-flipV = map reverse
+flipV pic = map reverse pic
-- Reflection in a horizontal mirror.
@@ -98,14 +99,14 @@
beside :: Picture -> Picture -> Picture
-beside = zipWith (++)
+beside pic1 pic2 = zipWith (++) pic1 pic2
-- Superimose one picture above another. Assume the pictures to be the same
-- size. The individual characters are combined using the combine function.
superimpose :: Picture -> Picture -> Picture
-superimpose = zipWith (zipWith combine)
+superimpose pic1 pic2 = zipWith (zipWith combine) pic1 pic2
-- For the result to be '.' both components have to the '.'; otherwise
-- get the '#' character.
@@ -121,7 +122,7 @@
invertColour :: Picture -> Picture
-invertColour = map (map invert)
+invertColour pic = map (map invert) pic
-- ... which works by making the result '.' unless the input is '.'.
diff --git a/Test.hs b/Test.hs
--- a/Test.hs
+++ b/Test.hs
@@ -16,3 +16,63 @@
pic2 :: Picture
pic2 = pic1 `above` invert pic1
+
+howManyEqual :: Integer -> Integer -> Integer -> Integer
+
+howManyEqual x y z
+ | x==y && y==z = 3
+ | x==y || y==z || z==x = 2
+ | otherwise = 0
+
+
+(^^^) :: Integer -> Integer -> Integer
+x ^^^ y
+ | x>= y = x
+ | otherwise = y
+
+fac :: Integer -> Integer
+
+fac 0 = 1
+fac n
+ | n>0 = n * fac (n-1)
+ | otherwise = 0
+
+
+
+maxThreeOccurs :: Integer -> Integer -> Integer -> (Integer,Integer)
+
+maxThreeOccurs x y z =
+ (theMax,occurs)
+ where
+ theMax = max (max x y) z
+ occurs = eq x + eq y + eq z
+ eq w = if w==theMax then 1 else 0
+
+pow :: Integer -> Integer
+
+pow n
+ | n==0 = 1
+ | n>0 = 2 * pow (n-1)
+ | otherwise = 0
+
+sumFun :: (Integer -> Integer) -> Integer -> Integer
+
+sumFun f n
+ | n==0 = f 0
+ | n>0 = sumFun f (n-1) + f n
+ | otherwise = 0
+
+
+fibP :: Integer -> (Integer,Integer)
+
+fibP 0 = (0,1)
+fibP n = (v,u+v)
+ where
+ (u,v) = fibP (n-1)
+
+
+fib :: Integer -> Integer
+
+fib 0 = 0
+fib 1 = 1
+fib n = fib (n-2) + fib (n-1)
diff --git a/svgOut.xml b/svgOut.xml
--- a/svgOut.xml
+++ b/svgOut.xml
@@ -9,9 +9,5 @@
-
-
-
-