Some minor fixes

I just noted that the example claiming that (add 10) is the same as (+10) was wrong. (A detail - it should be (10+) to match the argument order.) Then I just continued down making a few similar fixes and terminology updates. 
/Patrik

PS. I've been teaching [Advanced Functional Programming](http://www.cse.chalmers.se/edu/course/afp/) (in Haskell) for a few years at Chalmers.

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 [] = []