$ cat qqq
use QRegex;

sub compile_qast($qast) {
    my $post := QAST::Compiler.as_post($qast);
    my $pir := QAST::Compiler.pir($post);
    QAST::Compiler.evalpmc($pir);
}

sub compile($qast) {
    my $code := compile_qast($qast);
    $code();
}

compile(
    QAST::Block.new(
        QAST::Op.new(
            :op('bind'),
            QAST::Var.new( :name('$i'), :scope('lexical'), :decl('var') ),
            QAST::IVal.new( :value(5) )
        ),
        QAST::Op.new(
            :op('while'),
            QAST::Var.new( :name('$i'), :scope('lexical') ),
            QAST::Op.new(
                :op('bind'),
                QAST::Var.new( :name('$i'), :scope('lexical') ),
                QAST::Op.new(
                    :op('sub_i'),
                    QAST::Var.new( :name('$i'), :scope('lexical') ),
                    QAST::IVal.new( :value(1) )
                )
            ),
        ),
        QAST::Var.new( :name('$i'), :scope('lexical') ),
    ),
);

$ ./nqp qqq
Coercion from 'i' to 'p' NYI
current instr.: 'nqp;QAST;Compiler;coerce' pc 39282 (src/stage2/QRegex.pir:14760) (src/stage2/QRegex.nqp:1158)
called from Sub 'nqp;QAST;Compiler;_block2291' pc 38053 (src/stage2/QRegex.pir:14217) (src/stage2/QRegex.nqp:1043)
called from Sub 'nqp;QAST;Compiler;_block2286' pc 37947 (src/stage2/QRegex.pir:14171) (src/stage2/QRegex.nqp:1042)
called from Sub 'nqp;QAST;Compiler;as_post' pc 36378 (src/stage2/QRegex.pir:13554) (src/stage2/QRegex.nqp:1040)
called from Sub 'nqp;QAST;Compiler;as_post' pc 32721 (src/stage2/QRegex.pir:11972) (src/stage2/QRegex.nqp:849)
called from Sub '_block1891' pc 27737 (src/stage2/QRegex.pir:9638) (src/stage2/QRegex.nqp:386)
called from Sub 'nqp;QAST;Operations;_block1768' pc 24484 (src/stage2/QRegex.pir:8213) (src/stage2/QRegex.nqp:171)
called from Sub 'nqp;QAST;Operations;compile_op' pc 24345 (src/stage2/QRegex.pir:8135) (src/stage2/QRegex.nqp:171)
called from Sub 'nqp;QAST;Compiler;as_post' pc 35736 (src/stage2/QRegex.pir:13263) (src/stage2/QRegex.nqp:984)
called from Sub 'nqp;QAST;Compiler;as_post' pc 32721 (src/stage2/QRegex.pir:11972) (src/stage2/QRegex.nqp:849)
called from Sub 'nqp;QAST;Compiler;_block2253' pc 35656 (src/stage2/QRegex.pir:13225) (src/stage2/QRegex.nqp:974)
called from Sub 'nqp;QAST;Compiler;compile_all_the_stmts' pc 35548 (src/stage2/QRegex.pir:13170) (src/stage2/QRegex.nqp:974)
called from Sub 'nqp;QAST;Compiler;_block2178' pc 33894 (src/stage2/QRegex.pir:12471) (src/stage2/QRegex.nqp:868)
called from Sub 'nqp;QAST;Compiler;_block2158' pc 33149 (src/stage2/QRegex.pir:12176) (src/stage2/QRegex.nqp:866)
called from Sub 'nqp;QAST;Compiler;as_post' pc 32790 (src/stage2/QRegex.pir:12015) (src/stage2/QRegex.nqp:856)
called from Sub 'nqp;QAST;Compiler;as_post' pc 32721 (src/stage2/QRegex.pir:11972) (src/stage2/QRegex.nqp:849)
called from Sub 'compile_qast' pc 574 ((file unknown):201) (qqq:4)
called from Sub 'compile' pc 679 ((file unknown):245) (qqq:9)
called from Sub '_block1000' pc 387 ((file unknown):129) (qqq:15)
called from Sub 'nqp;HLL;Compiler;_block1775' pc 32432 (src/stage2/gen/NQPHLL.pir:12075) (src/stage2/gen/NQPHLL.pm:1269)
called from Sub 'nqp;HLL;Compiler;eval' pc 32243 (src/stage2/gen/NQPHLL.pir:11981) (src/stage2/gen/NQPHLL.pm:1259)
called from Sub 'nqp;HLL;Compiler;evalfiles' pc 35359 (src/stage2/gen/NQPHLL.pir:13518) (src/stage2/gen/NQPHLL.pm:1457)
called from Sub 'nqp;HLL;Compiler;_block1868' pc 34069 (src/stage2/gen/NQPHLL.pir:12887) (src/stage2/gen/NQPHLL.pm:1387)
called from Sub 'nqp;HLL;Compiler;command_eval' pc 33637 (src/stage2/gen/NQPHLL.pir:12701) (src/stage2/gen/NQPHLL.pm:1402)
called from Sub 'nqp;HLL;Compiler;command_line' pc 33259 (src/stage2/gen/NQPHLL.pir:12525) (src/stage2/gen/NQPHLL.pm:1353)
called from Sub 'MAIN' pc 15047 (src/stage2/gen/NQP.pir:4833) (src/stage2/gen/NQP.pm:2935)
called from Sub '_block1000' pc 201 (src/stage2/gen/NQP.pir:106) (src/stage2/gen/NQP.pm:1)