Tidy up

docs/lectures/compilers/05_functors.md

@@ -1,6 +1,6 @@
 # Functor
 
-Parsing an expression in parenthesis:
+Parsing an expression in parentheses:
 
 ```haskell
 parseP :: Parser AST
@@ -22,9 +22,9 @@ Before we write this sort of code, we need to understand `type classes` (especia
 | String | Functor      |
 |        | Monad        |
 
-**Eq**:  typeclass equality; A type can only be typeclass equality if two like types can be compared
+**Eq**: type class for equality; a type can only be in this type class if two values of that type can be compared
 
-A type can be a *member*  (instance) of a type class, meaning that if has the properties/functions that the class requires
+A type can be a *member* (instance) of a type class, meaning that it has the properties/functions that the class requires
 
 e.g. `Bool` is an instance of `Eq` and `Show`
 
@@ -61,7 +61,7 @@ newtype Parser a = P (String -> [a, String])
 
 **Parser AST** is a type
 
-Functor is a typeclass of which `parser` is an instance
+Functor is a type class of which `parser` is an instance
 
 ##### Functor
 
@@ -95,7 +95,4 @@ fmap id = id -- identity
 fmap (f . g) = fmap f . fmap g
 ```
 
-Haskell doesn't enforce these rules however it is convention.
-
-
-
+Haskell doesn't enforce these rules; however, following them is convention.