Re: [Erlang Forums] [Erlang/OTP Proposals/Proposals: RFC] Re-visiting EEP-0055

Fred Dushin <[email protected]> ezt =C3=ADrta (id=C5=91pont: 2022. =C3=A1pr. =
27., Sze, 15:14):
>
[...]
> But as noted later in the EEP, this can be written as
>
> f(X, Y) ->
>     F =3D fun ({a, Z}) when Z =3D:=3D Y  -> {ok, Y};
>             (_) -> error
>         end,
>     F(X).
[...]
> And not to be too critical, but I am having a hard time understanding par=
ts of the Rationale section.  The author(s) suggest(s) that in current Erla=
ng temporary variables are needed to achieve the same as the proposed glyph=
, but then provide an example that uses a guard (as above) but doesn't use =
a temporary variable, after all (?)

Z is the temporary variable in the above example.

> I am not sure what the problem is with temporary variables.  The compiler=
 has registers at its disposal, so I don't think it's a performance argumen=
t, but more an issue of readability, which again, I think is a purely aesth=
etic question, and has no bearing on the features of the language, per se. =
 In other words, the proposal is not suggesting anything that cannot alread=
y be achieved in current Erlang, with effectively the same compiled BEAM AS=
M.

Naming is hard, and if you have to come up with two meaningful
variable names instead of one, it's even harder. This leads to code
like this:

     F =3D fun ({a, TmpMeaningfulName}) when TmpMeaningfulName =3D:=3D
MeaningfulName  -> {ok, MeaningfulName};

The current solution in the language easily leads to too long lines or
overly verbose code.