R devel - Oct 2014 - Unexpected behavior of identical() with language objects

I ran into this and found the result very surprising:

identical( quote({ a }),  quote({ a }) )
# FALSE

It seems related to curly braces. For example, parens work fine:
identical( quote(( a )),  quote(( a )) )
# TRUE

Is this expected behavior? I can't seem to find anything in the help
for identical that relates to this.

-Winston

On Wed, Oct 29, 2014 at 3:26 PM, Winston Chang <winstonchang1 at
gmail.com> wrote:
> I ran into this and found the result very surprising:
>
> identical( quote({ a }),  quote({ a }) )
> # FALSE
>
> It seems related to curly braces. For example, parens work fine:
> identical( quote(( a )),  quote(( a )) )
> # TRUE
>
> Is this expected behavior? I can't seem to find anything in the help
> for identical that relates to this.
>
It's not in ?identical, but ?Paren gives you some pointers.
str(quote((a))) and str(quote({a})) are also informative.
> -Winston
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

-- 
Joshua Ulrich  |  about.me/joshuaulrich
FOSS Trading  |  www.fosstrading.com

Fascinating! I tried the comparisons with all.equal(), expecting a
description of the difference, but TRUE was returned in both cases.
Dave


On Wed, Oct 29, 2014 at 3:26 PM, Winston Chang <winstonchang1 at
gmail.com>
wrote:
> I ran into this and found the result very surprising:
>
> identical( quote({ a }),  quote({ a }) )
> # FALSE
>
> It seems related to curly braces. For example, parens work fine:
> identical( quote(( a )),  quote(( a )) )
> # TRUE
>
> Is this expected behavior? I can't seem to find anything in the help
> for identical that relates to this.
>
> -Winston
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
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