1 files changed, 20 insertions, 15 deletions

diff --git a/ocaml.html.markdown b/ocaml.html.markdown
index f9db7080..8faab297 100644
--- a/ocaml.html.markdown
+++ b/ocaml.html.markdown
@@ -34,13 +34,13 @@ For a source file you can use "ocamlc -i /path/to/file.ml" command
 to print all names and type signatures.
 
 ```
-$ cat sigtest.ml 
+$ cat sigtest.ml
 let inc x = x + 1
 let add x y = x + y
 
-let a = 1 
+let a = 1
 
-$ ocamlc -i ./sigtest.ml 
+$ ocamlc -i ./sigtest.ml
 val inc : int -> int
 val add : int -> int -> int
 val a : int
@@ -104,7 +104,7 @@ let fact_4 = factorial (5-1) ;;
 let sqr2 = sqr (-2) ;;
 
 (* Every function must have at least one argument.
-   Since some funcions naturally don't take any arguments, there's 
+   Since some funcions naturally don't take any arguments, there's
    "unit" type for it that has the only one value written as "()" *)
 let print_hello () = print_endline "hello world" ;;
 
@@ -144,11 +144,16 @@ x + y ;;
 (* Alternatively you can use "let ... and ... in" construct.
    This is especially useful for mutually recursive functions,
    with ordinary "let .. in" the compiler will complain about
-   unbound values.
-   It's hard to come up with a meaningful but self-contained
-   example of mutually recursive functions, but that syntax
-   works for non-recursive definitions too. *)
-let a = 3 and b = 4 in a * b ;;
+   unbound values. *)
+let rec
+  is_even = function
+  | 0 -> true
+  | n -> is_odd (n-1)
+and
+  is_odd = function
+  | 0 -> false
+  | n -> is_even (n-1)
+;;
 
 (* Anonymous functions use the following syntax: *)
 let my_lambda = fun x -> x * x ;;
@@ -191,7 +196,7 @@ let (~/) x = 1.0 /. x ;;
 ~/4.0 (* = 0.25 *)
 
 
-(*** Built-in datastructures ***)
+(*** Built-in data structures ***)
 
 (* Lists are enclosed in square brackets, items are separated by
    semicolons. *)
@@ -288,7 +293,7 @@ type int_list_list = int list_of_lists ;;
 (* Types can also be recursive. Like in this type analogous to
    built-in list of integers. *)
 type my_int_list = EmptyList | IntList of int * my_int_list ;;
-let l = Cons (1, EmptyList) ;;
+let l = IntList (1, EmptyList) ;;
 
 
 (*** Pattern matching ***)
@@ -296,7 +301,7 @@ let l = Cons (1, EmptyList) ;;
 (* Pattern matching is somewhat similar to switch statement in imperative
    languages, but offers a lot more expressive power.
 
-   Even though it may look complicated, it really boils down to matching 
+   Even though it may look complicated, it really boils down to matching
    an argument against an exact value, a predicate, or a type constructor.
    The type system is what makes it so powerful. *)
 
@@ -315,7 +320,7 @@ let is_one = function
 ;;
 
 (* Matching predicates, aka "guarded pattern matching". *)
-let abs x = 
+let abs x =
     match x with
     | x when x < 0 -> -x
     | _ -> x
@@ -336,10 +341,10 @@ let say x =
 
 say (Cat "Fluffy") ;; (* "Fluffy says meow". *)
 
-(** Traversing datastructures with pattern matching **)
+(** Traversing data structures with pattern matching **)
 
 (* Recursive types can be traversed with pattern matching easily.
-   Let's see how we can traverse a datastructure of the built-in list type.
+   Let's see how we can traverse a data structure of the built-in list type.
    Even though the built-in cons ("::") looks like an infix operator,
    it's actually a type constructor and can be matched like any other. *)
 let rec sum_list l =