What is begin…end in Erlang used for?

Question

I just stomped at a begin...end in Erlang\'s documentation (here), but it doesn\'t give some examples of how it is useful.

Looking here in StackOverflow I f

Answer 1

According to erlang documentation is it block expression that evaluates each expression but returns only the last one.

See this example (not using block expression):

A = 1,
case A + 1 of
    3 ->
        ok;
    _->
        nop
end.

% returns ok

Now you can define A within the case argument using block expression:

case begin A = 1, A + 1 end of
    3 ->
        ok;
    _->
        nop
end.

%returns ok

That evaluates A = 1, then returns the result of A + 1.

Now we know that this will not work:

case A = 1, A + 1 of
    3 ->
        ok;
    _->
        nop
end.

% returns syntax error before: ','