[eeps] EEP 049: Value-Based Error Handling Mechanisms

[Fred Hebert]

I would personally not go for ‘catch’ since its two current uses are for
exception handling whereas here it’s not the case at all.

On Fri, Oct 23, 2020 at 00:47 José Valim <jose.valim@REDACTED> wrote:

>
>
>> I don't know if we have a problem with introducing 'else' as a keyword.
>> Will that potentially break old existing code?
>>
>
> If a new keyword is a contention point, "catch" can be one option:
>
> change_and_backup(File) ->
>   begin
>     {ok, Value} <~ file:read_file(File),
>     NewValue = do_something_with_value(Value),
>     ok <~ file:write_file(File ++ ".backup", Value),
>     ok <~ file:write_file(File, NewValue),
>     NewValue
>   catch
>     {error, Reason} -> erlang:error({backup_error, Reason}, [File])
>   end.
>
> Use begin/catch for local/functional returns and try/catch for
> non-local/imperative returns.  It may even make it clearer they are two
> approaches for tackling the same problem.
>
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