From usikov@ziex.by

perl6 -v
This is Rakudo version 2017.01 built on MoarVM version 2017.01

sub f {
  my $i = 0;
  while True {
  FIRST { say "FIRST​: $i"};
  LAST { say "LAST​: $i"};
  last if ++$i > 100;
  }
}

doesn't compile​:
===SORRY!===
Cannot reference undeclared local 'LOOP_BLOCK_1'

without FIRST gives an error​:

sub f {
  my $i = 0;
  while True {
  # FIRST { say "FIRST​: $i"};
  LAST { say "LAST​: $i"};
  last if ++$i > 100;
  }
}

f();

LAST​: 0
No such method '!capture_phasers' for invocant of type 'Code'
  in block <unit> at t1.p6 line 16

in Promises compiles but gives random results​:

await do for 1..10 { start {
  my $i = 0;
  loop {
  FIRST { say "FIRST​: $i"};
  LAST { say "LAST​: $i"};
  last if ++$i > 100;
  }
} }

FIRST​: 0
FIRST​: 0
FIRST​: 2
FIRST​: 0
LAST​: 0
LAST​: 5
LAST​: 5
FIRST​: 0
FIRST​: 0
FIRST​: 64
LAST​: 103
LAST​: 103
LAST​: 103
FIRST​: 103
LAST​: 104
FIRST​: 2
FIRST​: 98
LAST​: 102
LAST​: 102
LAST​: 102

changing loop/while to for 1..* solves first two issues, but​:

using for 1..* instead of loop give more stable, but still sometimes incorrect results with promises​:

await do for 1..10 { start {
  my $i = 0;
  for 1..* {
  FIRST { say "FIRST​: $i"};
  LAST { say "LAST​: $i"};
  #say $i;
  last if ++$i > 100;
  }
} }

FIRST​: 0
FIRST​: 0
FIRST​: 77
FIRST​: 0
LAST​: 101
LAST​: 101
LAST​: 101
LAST​: 101
FIRST​: 0
FIRST​: 0
LAST​: 101
FIRST​: 0
LAST​: 101
FIRST​: 0
LAST​: 101
FIRST​: 0
LAST​: 101
FIRST​: 0
LAST​: 101
LAST​: 101