[erlang-questions] 答复: Is it a compiler bug?

赵 汉 botanyzh@REDACTED
Fri Apr 14 04:24:39 CEST 2017


I still don’t get the sense , What is the need for such weird appending use?

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发件人: Robert Virding<mailto:rvirding@REDACTED>
发送时间: 2017年4月14日 8:15
收件人: Dmytro Lytovchenko<mailto:dmytro.lytovchenko@REDACTED>
抄送: Erlang Questions<mailto:erlang-questions@REDACTED>; Stanislaw Klekot<mailto:dozzie@REDACTED>
主题: Re: [erlang-questions] Is it a compiler bug?

IIRC originally parentheses were required around the first was required which would have caught this case. The requirement was then removed, but I don't know why. Perhaps to save the extra 2 chars. :-)

On 13 April 2017 at 16:43, Dmytro Lytovchenko <dmytro.lytovchenko@REDACTED<mailto:dmytro.lytovchenko@REDACTED>> wrote:
I can see how enforcing parentheses in map()map() syntax can be useful.
A compiler warning would be awesome here. Also this is a nice thing for Elvis style checker to do, but when it comes to running Elvis, your program should already be correct ― so that is too late.

In variable()map() syntax there is no confusion so that is fine.

2017-04-13 16:14 GMT+02:00 Jesper Louis Andersen <jesper.louis.andersen@REDACTED<mailto:jesper.louis.andersen@REDACTED>>:
No, it is not stupidity in any way.

People hit this now and again. It makes sense to solve the problem this way. I remember we considered the alternative, which is to reject the notion, but this requires some special-handling in the compiler and isn't clear-cut either.

In short, regarding this as an invalid expression is to a certain extent possible, and certainly desirable. But we run into subtle problems when we want to reject it too, which is what complicates matters.

I think it is healthy to challenge certain design decisions in Erlang, especially because dynamically typed languages tend to have corner cases in their semantics which are hard to handle in general.

On Thu, Apr 13, 2017 at 4:04 PM Minin Maxim <Maxim.Minin@REDACTED<mailto:Maxim.Minin@REDACTED>> wrote:
I'm so stupid today :)
Thanks guys (Robert & Stanislaw)
Cheers
Maxim

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