Re: proposal sql: labeled function params

Hello

I understand now why Oracle use => symbol for named params. This isn't
used so operator - so implementation is trivial.
postgres=# create function x(a boolean) returns bool as $$select $1$$
language sql;
CREATE FUNCTION
Time: 5,549 ms
postgres=# select x(a => true);x
---t
(1 row)

Time: 0,566 ms
postgres=# select x(a => 0 >= 1);x
---f
(1 row)

Time: 0,772 ms
postgres=# select x(a => 0 <= 1);x
---t
(1 row)

Time: 0,633 ms
postgres=# select x(a => 0 <= 1);

it could live together with labels
postgres=# select x(a => 0 <= 1 as boo);x
---t
(1 row)

there are not any conflict. nice (operator => is never used).

I dislike to use AS for named params - it has some unhappy consequences:
a) it merge two features together (named params, labels),
b) when we disable @a, then we should implement only one feature - named params
c) @b isn't compatible with SQL/XML that is implemented now

I don't found any notice about db2 default parameters.

Named params needs different algorithm of searching in pg_proc. There
should be some new problems - like

create function foo(a integer, b integer);
select foo(10,10); -- ok
select foo(a => 10, b =>20); -- ok
select foo(b=>20, a =>20); -- ok
select foo(c=>20, 20); -- unknown fce !!!

Regards
Pavel Stehule

real gram implemenation:
param_list:    param                               {                                       $$ = list_make1($1);
                     }                       | param_list ',' param                               {
                 $$ = lappend($1, $3);                               }               ;
 

param:               a_expr                               {                                       $$ = $1;
                }               | param_name POINTER a_expr                               {
         $$ = $3;                               }               | a_expr AS ColLabel                               {
                                  $$ = $1;                               }               | param_name POINTER a_expr AS
ColLabel                              {                                       $$ = $3;                               }
            ;
 


lexer
identifier              {ident_start}{ident_cont}*

typecast                "::"
pointer                 "=>"