gistfile1.txt

[jdv@wieldy ~]$ cat test.p6
use v6;
use Test;

sub infix:<≈> ($a, $b, :$desc) {
    my $ok = $a ~~ $b;
    return $ok unless $desc;
    ok($ok, $desc);
    unless $ok {
        diag("expected: $b.perl()");
        diag("got:      $a");
    }
    return $ok;
}

sub infix:<±> ($num, $tolerance) is tighter(&infix:<≈>) {
    $num-$tolerance .. $num+$tolerance
}

say 2.25 ≈ 1.3 ± $_ for 0.5, 1;

2.25 ≈ 1.3 ± $_ :desc("foo $_") for 0.5, 1;

done-testing;
[jdv@wieldy ~]$ perl6 test.p6
False
True
not ok 1 - foo 0.5

# Failed test 'foo 0.5'
# at test.p6 line 7
# expected: 0.8..1.8
# got:      2.25
ok 2 - foo 1
1..2
# Looks like you failed 1 test of 2
[jdv@wieldy ~]$