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wtd

Mon Jul 03, 2006 12:02 pm


An Open Challenge

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For those looking for a language to learn who aren't enthralled with nostalgia by my recent C and Pascal tours, give Erlang a try.

My first Erlang program:

-module(hello).
-export([hello/1]).
-import(io).

hello(Name) ->
   io:format("Hello, ~s!~n", [Name]).

This was tested in the interpreter with:

1> c(hello).
{ok,hello}
2> hello:hello("wtd").
Hello, wtd!
ok

And a modification that uses pattern matching:

-module(hello).
-export([hello/1]).
-import(io).

hello("wtd") ->
   io:format("That cur!~n", []) ;
hello(Name) ->
   io:format("Hello, ~s!~n", [Name]).

A little more pattern matching, and recursion:

-module(hello).
-export([hello/1, greet/2]).
-import(io).

hello("wtd") ->
   io:format("That cur!~n", []) ;
hello(Name) ->
   io:format("Hello, ~s!~n", [Name]).

greet(_, []) ->
   {ok} ;
greet(Greeting, ["wtd"|Rest]) ->
   hello("wtd") ,
   greet(Greeting, Rest) ;
greet(Greeting, [First|Rest]) ->
   io:format("~s, ~s!~n", [Greeting, First]) ,
   greet(Greeting, Rest).

Some first-class functions:

Factorial = fun(N) -> 
               lists:foldl(fun(A, B) -> 
                              A * B 
                           end, 
                           1, lists:seq(1, N)) 
               end.