[erlang-bugs] Match error when mapping a list of maps with anonymous functions in the shell

[Anthony Ramine]

Because it makes the evaluation order relevant to scoping, while it shouldn’t be.

Compare with:

	[(fun (Y) -> X = Y end)(ok),X=not_ok].
	[case ok of ok -> X = ok; _ -> ok end,X=not_ok].

Also, Björn-Egil confirmed that the expression with the fun is indeed a bug. Nobody confirmed anything for the case with the unsafe X though.

The Erlang documentation agrees that there is no defined evaluation order.

And erl_lint agrees with me that the X in the fun shouldn’t match against the previous X, claiming both are unused.

In both cases, I think the X in the fun (or the case) shouldn’t match against anything and just be declared as unused by erl_lint.

Ideally, such code would just be forbidden by erl_lint because it is confusing.

-- 
Anthony Ramine

Le 4 mai 2014 à 13:00, Kostis Sagonas <kostis@REDACTED> a écrit :

> On 05/04/2014 11:13 AM, Anthony Ramine wrote:
>> Now the only remaining bug concerns some edge cases:
>> 
>> 	[X=not_ok,(fun (Y) -> X = Y end)(ok)].
>> 	[X=not_ok,case ok of ok -> X = ok; _ -> ok end].
>> 
>> In my opinion, in both cases the second X shouldn’t be matched against the first.
> 
> Why not?  Care to elaborate what is your rationale and what should happen in these cases?
> 
> Kostis
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