# New Ticket Created by "Carl Mäsak"
# Please include the string: [perl #115566]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=115566 >
<jnthn> r: macro infix:<pos-or>(*@asts) is assoc('list') { my $result =
@asts.pop; for @asts.reverse { $result := quasi{ {{{$_}}} > 0 ?? {{{$_}}}
!! {{{$result}}} } }; $result }; sub foo() { say "oops"; 4 }; say -5 pos-or
3 pos-or foo;
<p6eval> rakudo 2bb302: OUTPUT«3»
<jnthn> Using two of the month's new features together :P
<masak> that's pretty impressive.
<jnthn> Sadly, fixing the double evaluation exposes a bug.
<jnthn> r: macro infix:<pos-or>(*@asts) is assoc('list') { my $result =
@asts.pop; for @asts.reverse { $result := quasi { my \x = {{{$_}}}; x > 0
?? x !! {{{$result}}} } }; $result }; sub foo() { say "oops"; 4 }; say -5
pos-or 3 pos-or foo;
<p6eval> rakudo 2bb302: OUTPUT«Lexical 'x' not found in at
/tmp/tiE6e4uirM:1 in block at /tmp/tiE6e4uirM:1»
<masak> "the double evaluation"?
<jnthn> masak: It evalutes the macro argument twice.
<jnthn> masak: Because I wrote it that way
<masak> oh!
<masak> (phew)
<jnthn> {{{$_}}} > 0 ?? {{{$_}}} !! ...
<masak> yes, each {{{}}} evaluates once.
<jnthn> And I wanted to just do it once, but when I try to stick it in a
temporary variable, it busts.
<masak> as above. I see.
<masak> maybe declaring variables in quasis doesn't work?
<jnthn> Seems so
<masak> r: macro foo { quasi { my $a = "OH HAI"; say $a } }; foo
<p6eval> rakudo 2bb302: OUTPUT«Cannot assign into a PMCNULL container [...]
* masak submits rakudobug
