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@ -189,16 +189,16 @@ foo = add 10 -- foo is now a function that takes a number and adds 10 to it
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foo 5 -- 15
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-- Another way to write the same thing
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foo = (+10)
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foo = (10+)
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foo 5 -- 15
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-- function composition
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-- the operator `.` chains functions together.
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-- For example, here foo is a function that takes a value. It adds 10 to it,
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-- multiplies the result of that by 4, and then returns the final value.
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foo = (*4) . (+10)
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foo = (4*) . (10+)
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-- (5 + 10) * 4 = 60
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-- 4*(10 + 5) = 60
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foo 5 -- 60
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-- fixing precedence
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@ -222,7 +222,7 @@ even . fib $ 7 -- false
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-- 5. Type signatures
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----------------------------------------------------
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-- Haskell has a very strong type system, and everything has a type signature.
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-- Haskell has a very strong type system, and every valid expression has a type.
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-- Some basic types:
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5 :: Integer
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@ -259,7 +259,7 @@ case args of
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_ -> putStrLn "bad args"
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-- Haskell doesn't have loops; it uses recursion instead.
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-- map applies a function over every element in an array
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-- map applies a function over every element in a list
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map (*2) [1..5] -- [2, 4, 6, 8, 10]
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@ -279,7 +279,7 @@ foldl (\x y -> 2*x + y) 4 [1,2,3] -- 43
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-- This is the same as
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(2 * (2 * (2 * 4 + 1) + 2) + 3)
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-- foldl is left-handed, foldr is right-
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-- foldl is left-handed, foldr is right-handed
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foldr (\x y -> 2*x + y) 4 [1,2,3] -- 16
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-- This is now the same as
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@ -318,7 +318,7 @@ Nothing -- of type `Maybe a` for any `a`
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-- it is not hard to explain enough to get going.
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-- When a Haskell program is executed, `main` is
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-- called. It must return a value of type `IO ()`. For example:
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-- called. It must return a value of type `IO a` for some type `a`. For example:
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main :: IO ()
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main = putStrLn $ "Hello, sky! " ++ (say Blue)
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@ -361,7 +361,7 @@ sayHello = do
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-- You can think of a value of type `IO a` as representing a
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-- computer program that will generate a value of type `a`
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-- when executed (in addition to anything else it does). We can
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-- store and reuse this value using `<-`. We can also
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-- name and reuse this value using `<-`. We can also
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-- make our own action of type `IO String`:
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action :: IO String
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@ -432,7 +432,7 @@ Hello, Friend!
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There's a lot more to Haskell, including typeclasses and monads. These are the
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big ideas that make Haskell such fun to code in. I'll leave you with one final
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Haskell example: an implementation of quicksort in Haskell:
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Haskell example: an implementation of a quicksort variant in Haskell:
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```haskell
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qsort [] = []
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