adjustments to functions.hs

functions.hs

@@ -1,69 +1,35 @@
-vals = (3, 7)
+next x = x + 1
 
-f x = (x, x + 1)
+hypotenuse x y = sqrt (x^2 + y^2)
 
-g :: (Num a) => a -> (a, a)
-g x = (x+1, x)
+greet name = "hello" ++ " " ++ name
 
--- to show that type signatures are optional
-greetings :: String -> String
-greetings name = "hello" ++ " " ++ name
+greet2 :: String -> String
+greet2 name = "hello" ++ " " ++ name
 
-greet name = "hello" ++ " " ++ name
+greetNext x = (next x, greet (show (next x)))
 
--- pattern matching
 hello :: String -> String
-hello "Olafur"     = "hello, Olafur!"
+hello "Olafur" = "hello, Olafur!"
 hello "Rocamadour" = "hey!"
-hello _            = "Nice to meet you!"
-
-
-myDouble  x = (if x > 145 then x else x*2) + 1
-myDouble' x = if x > 145
-                        then x
-                        else x*2
-
--- show how to define functions using lambdas
-notLambda = \x y -> x + y
-
--- recursion
-factorial :: (Intergal a) => a -> a
-factorial 0 = 1
-factorial n = n * factorial (n-1)
-
+hello x = greet x
 
 main =
   do
-    let (a, b) = vals
-    putStrLn (show a)
-    putStrLn (show b)
+    putStrLn (show (next 4))
+    putStrLn (show (next (next 4)))
 
-    let (_, c) = f 4
-    putStrLn (show c)
+    putStrLn (show (hypotenuse 3 4))
 
-    let (d, _) = g 4
-    putStrLn (show d)
+    putStrLn (greet "world")
+    putStrLn (greet2 "world")
 
-    let y = myDouble 1
-    putStrLn (show y)
-    let y' = myDouble 146
-    putStrLn (show y')
-    let z = myDouble' 1
-    putStrLn (show z)
-    let z = myDouble' 146
-    putStrLn (show z')
+    putStrLn (show (greetNext 7))
+
+    let (x, y) = greetNext 7
+    putStrLn (show x)
+    putStrLn y
 
-    putStrLn (greet "world")
-    putStrLn (greetings "world")
     putStrLn (hello "Olafur")
     putStrLn (hello "Rocamadour")
     putStrLn (hello "Jane")
-
-    let t = notLambda 1 2
-    putStrLn (show t)
-
-    let k = factorial 5
-    putStrLn (show k)
-
-    -- when lambdas are convenient
-    map (\x -> x*x - 1) [1..5]

outputs/functions.txt

@@ -0,0 +1,11 @@
+5
+6
+5.0
+hello world
+hello world
+(8,"hello 8")
+8
+hello 8
+hello, Olafur!
+hey!
+hello Jane

partial-application.hs

@@ -1,3 +1,6 @@
+    map next [1..5]
+    map (\x -> x + 1) [1..5]
+
 -- CURRYING:
 -- f :: X ->  Y ->  Z -> A
 -- is the same as

tools/outputs.nix

@@ -24,6 +24,7 @@ in
         (run "crypto-hashing.txt" ../crypto-hashing.hs {})
         (run "dynamic.txt" ../dynamic.hs {})
         (run "for-loops.txt" ../for-loops.hs {})
+        (run "functions.txt" ../functions.hs {})
         (run "hashing.txt" ../hashing.hs {})
         (run "hello-world.txt" ../hello-world.hs {})
         (run "mutable-references.txt" ../mutable-references.hs {})