* Re: [9fans] rc: fn name @{block}
[not found] <CAG3N4d81u5p-WVz5aXnjGE8ON5BMd-AEr0xRMjP+Ug4G9Db=UA@mail.gmail.c>
2012-03-30 12:52 ` [9fans] rc: fn name @{block} erik quanstrom
@ 2012-03-30 15:48 ` erik quanstrom
2012-03-30 15:56 ` Yaroslav
[not found] ` <CAG3N4d_5f97O85mwGnrawwiGQAPN+K6CTQ0vbpk2EexkpbH0qg@mail.gmail.c>
1 sibling, 2 replies; 8+ messages in thread
From: erik quanstrom @ 2012-03-30 15:48 UTC (permalink / raw)
To: 9fans
On Fri Mar 30 07:44:12 EDT 2012, yarikos@gmail.com wrote:
> "fn name @{block}" doesn't cause block to run in a sub-shell, although
> it accepts the syntax.
> Is it someting should not be tried, or something shoud be fixed?
you've misunderstood the current grammar. you have defined 2 functions
name and '@' as {block}. the binding, illustrated with parens is
fn (name @) {block}
the production in the grammer is
FN words brace
but since once production for words is words -> keyword, a keyword
is a valid function name.
so if you have
fn @{echo hi, mom}
then
ladd; fn @{echo hi, mom} # space makes no difference
ladd; whatis @
fn @ {echo hi, mom}
ladd; @
ladd; '@'
hi, mom
one could argue that this is a misfeature, since you can define
a function named 'for' or 'if' or '~' or '!'. i don't currently see how disallowing
keywords in function names would be a problem, but it would
require at least 1 new production in the grammar.
note that "fn {echo bar}" is also legal, but doesn't do anything.
i've attached a change to the grammar that addresses this oddity.
- erik
----
broken! diffy -c syn.y
/n/dump/2012/0330/sys/src/cmd/rc/syn.y:29,35 - syn.y:29,35
struct tree *tree;
};
%type<tree> line paren brace body cmdsa cmdsan assign epilog redir
- %type<tree> cmd simple first word comword keyword words wordsnl
+ %type<tree> cmd simple first word nkword comword keyword nkwords words wordsnl
%type<tree> NOT FOR IN WHILE IF TWIDDLE BANG SUBSHELL SWITCH FN BREAK
%type<tree> WORD REDIR DUP PIPE
%%
/n/dump/2012/0330/sys/src/cmd/rc/syn.y:81,88 - syn.y:81,88
| assign cmd %prec BANG {$$=mung3($1, $1->child[0], $1->child[1], $2);}
| BANG cmd {$$=mung1($1, $2);}
| SUBSHELL cmd {$$=mung1($1, $2);}
- | FN words brace {$$=tree2(FN, $2, $3);}
- | FN words {$$=tree1(FN, $2);}
+ | FN nkwords brace {$$=tree2(FN, $2, $3);}
+ | FN nkwords {$$=tree1(FN, $2);}
simple: first
| simple word {$$=tree2(ARGLIST, $1, $2);}
| simple redir {$$=tree2(ARGLIST, $1, $2);}
/n/dump/2012/0330/sys/src/cmd/rc/syn.y:91,96 - syn.y:91,98
word: keyword {lastword=1; $1->type=WORD;}
| comword
| word '^' word {$$=tree2('^', $1, $3);}
+ nkword: comword
+ | word '^' word {$$=tree2('^', $1, $3);}
comword: '$' word {$$=tree1('$', $2);}
| '$' word SUB words ')' {$$=tree2(SUB, $2, $4);}
| '"' word {$$=tree1('"', $2);}
/n/dump/2012/0330/sys/src/cmd/rc/syn.y:107,109 - syn.y:109,113
|
words: {$$=(struct tree*)0;}
| words word {$$=tree2(WORDS, $1, $2);}
+ nkwords: {$$=(struct tree*)0;}
+ | nkwords nkword {$$=tree2(WORDS, $1, $2);}
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] rc: fn name @{block}
2012-03-30 15:48 ` erik quanstrom
@ 2012-03-30 15:56 ` Yaroslav
[not found] ` <CAG3N4d_5f97O85mwGnrawwiGQAPN+K6CTQ0vbpk2EexkpbH0qg@mail.gmail.c>
1 sibling, 0 replies; 8+ messages in thread
From: Yaroslav @ 2012-03-30 15:56 UTC (permalink / raw)
To: Fans of the OS Plan 9 from Bell Labs
> you've misunderstood the current grammar. you have defined 2 functions
> name and '@' as {block}. the binding, illustrated with parens is
> fn (name @) {block}
> the production in the grammer is
> FN words brace
> but since once production for words is words -> keyword, a keyword
> is a valid function name.
Then, how would you explain this:
term% fn x @{x=y}
term% whatis x
fn x {x=y}
term% fn 'x @'{x=y}
term% whatis 'x @'
fn 'x @' {x=y}
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] rc: fn name @{block}
[not found] ` <CAG3N4d_5f97O85mwGnrawwiGQAPN+K6CTQ0vbpk2EexkpbH0qg@mail.gmail.c>
@ 2012-03-30 16:01 ` erik quanstrom
2012-03-30 16:19 ` Yaroslav
0 siblings, 1 reply; 8+ messages in thread
From: erik quanstrom @ 2012-03-30 16:01 UTC (permalink / raw)
To: 9fans
> Then, how would you explain this:
it should be self-explanitory.
> term% fn x @{x=y}
> term% whatis x
> fn x {x=y}
creates to functions x and '@' definition {x=y}.
> term% fn 'x @'{x=y}
> term% whatis 'x @'
> fn 'x @' {x=y}
quoting disables any interpretation in rc; this isn't
the bourne shell. what the parser sees is the following
tokens.
FN WORD '{' WORD '=' WORD '}'
in this case 'x' for some x should be interpreted
differently than for shell input. the *name* of the token
is 'x', not its value. (such tokens typically have no value.)
it does not matter that the first WORD is
defined as 'x @'.
- erik
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] rc: fn name @{block}
2012-03-30 16:01 ` erik quanstrom
@ 2012-03-30 16:19 ` Yaroslav
2012-03-30 16:50 ` Anthony Sorace
0 siblings, 1 reply; 8+ messages in thread
From: Yaroslav @ 2012-03-30 16:19 UTC (permalink / raw)
To: Fans of the OS Plan 9 from Bell Labs
>> term% fn x @{x=y}
>> term% whatis x
>> fn x {x=y}
>
> creates to functions x and '@' definition {x=y}.
The question is why it discards @ here?
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] rc: fn name @{block}
2012-03-30 16:19 ` Yaroslav
@ 2012-03-30 16:50 ` Anthony Sorace
2012-03-30 17:08 ` Yaroslav
0 siblings, 1 reply; 8+ messages in thread
From: Anthony Sorace @ 2012-03-30 16:50 UTC (permalink / raw)
To: Fans of the OS Plan 9 from Bell Labs
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On Mar 30, 2012, at 12:19 , Yaroslav wrote:
>>> term% fn x @{x=y}
>>> term% whatis x
>>> fn x {x=y}
>>
>> creates to functions x and '@' definition {x=y}.
>
> The question is why it discards @ here?
Erik's point is that rc isn't discarding it. You have a list. It sets x
equal to that function, then sets @ equal to that same function.
: iota; fn x @{x=y}
: iota; whatis x
fn x {x=y}
: iota; whatis '@'
fn @ {x=y}
When you quote the 'x @', that whole thing becomes one word.
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] rc: fn name @{block}
2012-03-30 16:50 ` Anthony Sorace
@ 2012-03-30 17:08 ` Yaroslav
0 siblings, 0 replies; 8+ messages in thread
From: Yaroslav @ 2012-03-30 17:08 UTC (permalink / raw)
To: Fans of the OS Plan 9 from Bell Labs
I see now. Thank you guys!
> Erik's point is that rc isn't discarding it. You have a list. It sets x
> equal to that function, then sets @ equal to that same function.
>
> : iota; fn x @{x=y}
> : iota; whatis x
> fn x {x=y}
> : iota; whatis '@'
> fn @ {x=y}
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [9fans] rc: fn name @{block}
[not found] <CAG3N4d81u5p-WVz5aXnjGE8ON5BMd-AEr0xRMjP+Ug4G9Db=UA@mail.gmail.c>
@ 2012-03-30 12:52 ` erik quanstrom
2012-03-30 15:48 ` erik quanstrom
1 sibling, 0 replies; 8+ messages in thread
From: erik quanstrom @ 2012-03-30 12:52 UTC (permalink / raw)
To: 9fans
On Fri Mar 30 07:43:57 EDT 2012, yarikos@gmail.com wrote:
> "fn name @{block}" doesn't cause block to run in a sub-shell, although
> it accepts the syntax.
> Is it someting should not be tried, or something shoud be fixed?
should be fixed.
- erik
^ permalink raw reply [flat|nested] 8+ messages in thread
* [9fans] rc: fn name @{block}
@ 2012-03-30 11:43 Yaroslav
0 siblings, 0 replies; 8+ messages in thread
From: Yaroslav @ 2012-03-30 11:43 UTC (permalink / raw)
To: 9fans
"fn name @{block}" doesn't cause block to run in a sub-shell, although
it accepts the syntax.
Is it someting should not be tried, or something shoud be fixed?
^ permalink raw reply [flat|nested] 8+ messages in thread
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2012-03-30 12:52 ` [9fans] rc: fn name @{block} erik quanstrom
2012-03-30 15:48 ` erik quanstrom
2012-03-30 15:56 ` Yaroslav
[not found] ` <CAG3N4d_5f97O85mwGnrawwiGQAPN+K6CTQ0vbpk2EexkpbH0qg@mail.gmail.c>
2012-03-30 16:01 ` erik quanstrom
2012-03-30 16:19 ` Yaroslav
2012-03-30 16:50 ` Anthony Sorace
2012-03-30 17:08 ` Yaroslav
2012-03-30 11:43 Yaroslav
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