Version française
Home     About     Download     Resources     Contact us    
Browse thread
New to Ocaml
[ Home ] [ Index: by date | by threads ]
[ Search: ]

[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: -- (:)
From: Miguel Pignatelli <miguel.pignatelli@u...>
Subject: Re: [Caml-list] New to Ocaml
 >    let sorted_list = List.sort unsorted_list in ....

You should also provide to List.sort a function to compare the elements 
of the list, the function should have type:

'a -> 'a -> int

For basic types, like ints or chars the Pervasives.compare function 
would serve:

# let l  = ['g';'b';'f';'c';'a'];;
val l : char list = ['g'; 'b'; 'f'; 'c'; 'a']
# let sortedl = List.sort compare l;;
val sortedl : char list = ['a'; 'b'; 'c'; 'f'; 'g']

For user-defined types (or if you want to write your own comparison 
criteria) you should provide the comparison function. For example;

# let sortedl = List.sort (fun x y -> if x > y then 1 else 0) [5;3;7;1];;
val sortedl : int list = [1; 3; 5; 7]


Hope this helps,

M;


Erik de Castro Lopo wrote:
> chaithanya kr wrote:
> 
>> Hi all. I am new to Ocaml. Just started learning recently.
>>
>> I was studying lists in ocaml. In that, suppose there is a list by name
>> singly_list, then by saying "List.length singly_list;;" I will get the
>> length of the linked list.
>>
>> Similarly can anyone tell me as to how to sort a linked list using the
>> 'sort' function? Please give me an example of using List.sort.
> 
> In Ocaml, lists are immutable (cannot be changed) and hence, sorting
> a list results in a new list:
> 
>    let sorted_list = List.sort unsorted_list in ....
> 
> Erik