Question

This is the case:

% print/1: Prints out the integers between 1 and N
print(0) ->   io:format("~w~n", [0]);
print(N) when is_integer(N) -> 
          io:format("~w~n", [N]),
          print(N - 1).

If the user inputs a non-integer, this happens:

11> effects:print('alfalfa').
** exception error: no function clause matching effects:print(alfalfa)

Is about phylosophy: Should I correct my program this way, in order to ‘catch all’ kinds of input?

% print/1: Prints out the integers between 1 and N
print(0) ->   io:format("~w~n", [0]);
print(N) when is_integer(N) -> 
          io:format("~w~n", [N]),
          print(N - 1).
% Last Line added:
print(_Other) -> false.

I’m new in erlang. Is there some convention for dealing with this?

Thanks!

Answer 1

In Erlang you mostly would not catch such bad API usages. If no pattern matches the invocation, an exception of class exit with a rather verbose message would be thrown ({function_clause, CallStack}).
Almost every standard library method throws. At the moment I fail to think of counterexamples.

Btw: You mostly would return {error, Msg}, not false, if there was some sort of error (mostly not usage error). In good cases ok or {ok, Datum} would be returned.