update page

docs/code/src/lec_10_10_23.hs

@@ -1,11 +1,39 @@
 module Lec_10_10_23 where
+import Data.Time.Format.ISO8601 (yearFormat)
 
+-- >>> 1 + 2
+-- 3
+
+-- >>> tails0 [1,2,3]
 
-thing1 :: Integer
-thing1 = 2
 
 thing2 :: Double
 thing2 = 5.1 + 6.9
 
 thing3 :: Bool
 thing3 = True
+
+thing4 :: Char
+thing4 = 'c'
+
+ex0 = 5 > 4
+
+thing1 :: Integer
+thing1 = 2 * (5 + 6)
+
+-- quiz = if ex0 then thing1 else 20
+
+--  Type_of_INPUT -> Type_of_OUTPUT
+
+quiz :: Bool -> Integer
+quiz mickeymouse = if mickeymouse then thing1 else 0
+
+
+add3 :: Integer -> Integer -> Integer -> Integer
+add3 x y z = x + y + z
+
+bob :: (Integer, Bool)
+bob = (10 + 12, True)
+
+bob3 :: (Integer, Bool, Char)
+bob3 = (10 + 12, True, 'd')

docs/code/src/lec_10_12_23.hs

@@ -0,0 +1,263 @@
+module Lec_10_12_23 where
+import Data.Time.Format.ISO8601 (yearFormat)
+
+-- >>> 1 + 2
+-- 3
+
+-- >>> tails0 [1,2,3]
+
+
+thing2 :: Double
+thing2 = 5.1 + 6.9
+
+thing3 :: Bool
+thing3 = True
+
+thing4 :: Char
+thing4 = 'c'
+
+ex0 = 5 > 4
+
+thing1 :: Integer
+thing1 = 2 * (5 + 6)
+
+-- quiz = if ex0 then thing1 else 20
+
+--  Type_of_INPUT -> Type_of_OUTPUT
+
+quiz :: Bool -> Integer
+quiz mickeymouse = if mickeymouse then thing1 else 0
+
+
+add3 :: Integer -> Integer -> Integer -> Integer
+add3 x y z = x + y + z
+
+bob :: (Integer, Bool)
+bob = (10 + 12, True)
+
+bob3 :: (Integer, Bool, Char)
+bob3 = (10 + 12, True, 'd')
+
+
+-- (e1, e2, e3) :: (T1, T2, T3)
+
+tup1 :: (Char, Integer)
+tup1 = ('a', 5)
+
+
+tup3 :: ((Int, Double), Bool)
+tup3 = ((7, 5.2), True)
+
+blob :: Int
+blob = 12
+
+
+getFst4 :: (a, b,c,d) -> a
+getFst4 (x1, x2, x3, x4) = x1
+
+getSnd4 :: (a, b, c, d) -> b
+getSnd4 (x1, x2, x3, x4) = x2
+
+-- >>> getSnd4 (1, "horse", 4.5, True)
+-- "horse"
+
+tup2 :: (Char, Double, Int)
+tup2 = ('a', 5.2, 7)
+
+snd3 :: (t1, t2, t3) -> t2
+snd3 (x1, x2, x3) = x2
+
+{-
+    snd3 tup2
+    =>
+    snd3 ('a', 5.2, 7)
+    =>
+    5.2
+
+-}
+
+chars :: [Char]
+chars = ['a','b','c']
+        -- ('a' : ('b' : ('c' : [])))
+
+bools :: [Bool]
+bools = [True, True, False, False, True]
+
+l1 :: [Int]
+l1 = [1,2,3]
+
+l2 :: [Int]
+l2 = 1 : 2 : 3 : []
+
+
+-- >>> l1 == l2
+-- True
+
+
+
+-- oops = [True, False, 'c']
+
+-- getNth :: Int -> [Stuff] -> Stuff
+-- getNth l n = returns the 'nth' element of l
+
+{-
+blobs :: [(Int, Int)]
+blobs = [(1,2),(3,4),(5,6)]
+
+-}
+
+
+
+--   takes an input x and
+--   returns a list with three copies of x
+
+copy3 :: t -> [t]
+copy3 x = [x,x,x]
+
+-- >>> copy3 "cat"
+-- ["cat","cat","cat"]
+
+
+-- >>> clone 1 "dog"
+-- ["dog"]
+
+-- >>> "wom" == ['w', 'o', 'm']
+-- True
+
+-- >>> getNth 100005 (clone (-1) "dog")
+-- "dog"
+{-
+   getNth 105 (clone (-1) "dog")
+   ==
+   getNth 1 ("dog" : clone (-2) "dog")
+   ==
+   getNth 1 ("dog" : "dog" : clone (-3) "dog")
+   ==
+   getNth 1 ("dog" : "dog" : "dog" : clone (-4) "dog")
+   ==
+   getNth 0 (        "dog" : "dog" : clone (-4) "dog")
+   ==
+   "dog"
+
+-}
+
+-- (1) undefined?
+-- (2) looping looping ...
+-- (3) type error
+-- (4) "dog"
+
+clone :: Int -> String -> [String]
+clone 0 x = []
+clone n x = x : clone (n-1) x
+
+myHead :: [a] -> a
+myHead []     = undefined
+myHead (x:xs) = x
+
+-- getNth 0 (x:xs) = x
+-- getNth n (x:xs) = getNth (n-1) xs
+
+-- getNth n (x:xs) = if n == 0 then x else getNth (n-1) xs
+
+getNth :: Int -> [a] -> a
+getNth n (x:xs)
+  | n == 0    = x
+  | otherwise = getNth (n-1) xs
+
+-- >>> range 0 3
+-- [0,1,2,3]
+
+-- >>> sumList  ['c', 'a', 't']
+
+-- range 4  3 =            []
+-- range 3  3 =         3 : []
+-- range 2  3 =     2 : 3 : []
+-- range 1  3 = 1 : 2 : 3 : []
+range :: Int -> Int -> [Int]
+range lo hi
+  | lo > hi   = []
+  | otherwise = lo : range (lo+1) hi
+
+
+mystery :: [a] -> Int
+mystery []     = 0
+mystery (x:xs) = 1 + mystery xs
+
+
+-- sumList :: Num a => [a] -> a
+sumList []     = 0
+sumList (x:xs) = x + sumList xs
+
+{- mystery (10:20:30:[])
+  =
+   1 + mystery (20:30:[])
+  =
+   1 + (1 + mystery (30:[]))
+  =
+   1 + (1 + (1 + mystery []))
+  =
+   1 + (1 + (1 + 0))
+  =
+   3
+
+-}
+
+type Circle = (Double, Double, Double)
+
+circle0 :: Circle
+circle0 = (0,0, 5)
+
+-- >>> circleArea circle0
+-- 78.53981633974483
+
+circleArea :: Circle -> Double
+circleArea (x, y, r) = pi * r * r
+
+type Cuboid = (Double, Double, Double)
+
+cub0 :: Cuboid
+cub0 = (10, 20, 30)
+
+-- >>> cubVolume cub0
+-- 6000.0
+
+cubVolume :: Cuboid -> Double
+cubVolume (l, b, h) = l * b * h
+
+-- >>> cubVolume circle0
+-- 0.0
+
+data CircleT = MkCircle Double Double Double
+
+cir1 :: CircleT
+cir1 = c 0 0 5
+
+-- >>> vol cir1
+-- Couldn't match expected type `CuboidT' with actual type `CircleT'
+-- In the first argument of `vol', namely `cir1'
+-- In the expression: vol cir1
+-- In an equation for `it_a3woO': it_a3woO = vol cir1
+
+area :: CircleT -> Double
+area (MkCircle x y r) = pi * r * r
+
+c :: Double -> Double -> Double -> CircleT
+c x y r = MkCircle x y r
+
+data CuboidT = MkCuboid Double Double Double
+
+data CC = MkCC { len :: Double, br :: Double, ht :: Double }
+
+vol' :: CC -> Double
+vol' c = len c * br c * ht c
+
+vol :: CuboidT -> Double
+vol (MkCuboid l b h) = l * b * h
+
+cub1 :: CuboidT
+cub1 = MkCuboid 10 20 30
+
+
+-- area' :: CircleT -> Double
+-- area' a  = case a of
+--              MkCuboid x y r -> pi * r * r