diff options
| -rw-r--r-- | haskell.html.markdown | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/haskell.html.markdown b/haskell.html.markdown index 08611e63..2f58b357 100644 --- a/haskell.html.markdown +++ b/haskell.html.markdown @@ -189,16 +189,16 @@ foo = add 10 -- foo is now a function that takes a number and adds 10 to it foo 5 -- 15 -- Another way to write the same thing -foo = (+10) +foo = (10+) foo 5 -- 15 -- function composition -- the (.) function chains functions together. -- For example, here foo is a function that takes a value. It adds 10 to it, -- multiplies the result of that by 4, and then returns the final value. -foo = (*4) . (+10) +foo = (4*) . (10+) --- (5 + 10) * 4 = 60 +-- 4*(10 + 5) = 60 foo 5 -- 60 -- fixing precedence @@ -222,7 +222,7 @@ even . fib $ 7 -- false -- 5. Type signatures ---------------------------------------------------- --- Haskell has a very strong type system, and everything has a type signature. +-- Haskell has a very strong type system, and every valid expression has a type. -- Some basic types: 5 :: Integer @@ -259,7 +259,7 @@ case args of _ -> putStrLn "bad args" -- Haskell doesn't have loops; it uses recursion instead. --- map applies a function over every element in an array +-- map applies a function over every element in a list map (*2) [1..5] -- [2, 4, 6, 8, 10] @@ -279,7 +279,7 @@ foldl (\x y -> 2*x + y) 4 [1,2,3] -- 43 -- This is the same as (2 * (2 * (2 * 4 + 1) + 2) + 3) --- foldl is left-handed, foldr is right- +-- foldl is left-handed, foldr is right-handed foldr (\x y -> 2*x + y) 4 [1,2,3] -- 16 -- This is now the same as @@ -318,7 +318,7 @@ Nothing -- of type `Maybe a` for any `a` -- it is not hard to explain enough to get going. -- When a Haskell program is executed, `main` is --- called. It must return a value of type `IO ()`. For example: +-- called. It must return a value of type `IO a` for some type `a`. For example: main :: IO () main = putStrLn $ "Hello, sky! " ++ (say Blue) @@ -361,7 +361,7 @@ sayHello = do -- You can think of a value of type `IO a` as representing a -- computer program that will generate a value of type `a` -- when executed (in addition to anything else it does). We can --- store and reuse this value using `<-`. We can also +-- name and reuse this value using `<-`. We can also -- make our own action of type `IO String`: action :: IO String @@ -417,7 +417,7 @@ Hello, Friend! There's a lot more to Haskell, including typeclasses and monads. These are the big ideas that make Haskell such fun to code in. I'll leave you with one final -Haskell example: an implementation of quicksort in Haskell: +Haskell example: an implementation of a quicksort variant in Haskell: ```haskell qsort [] = [] |