Erlang (programming language)/Tutorials/Functions

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Syntax of functions

Functions are defined by the domain of the arguments and the number of arguemnts. A function ends with a period. A function defined over differnt domains are separated by semicolons. A fact function gives an answer that is sensitive to the domain of the input. With strings it gives a fact. With counting numbers it gives the factorial function.

fact("aloha") -> "Aloha is a greating";
fact(String) when is_a_list(String) -> 
    "no fact is known about " ++ String;
fact(0) -> 1;
fact(N) when is_integer(N) and (N > 0) -> 
    fact(N-1)*N;
fact(N) when N < 0 -> error.