How do I decompress a Git object properly in Raku Perl 6?

Question

I have the following Python code snippet:

import zlib

def object_read(repo, sha):
    path = repo + "/objects/" + sha[0:2] +  "/" + sha[2:]

    with open (path, "rb") as f:
        raw = zlib.decompress(f.read())
        return len(raw)

print(object-read(".git", "1372c654fd9bd85617f0f8b949f1405b0bd71ee9"))

and one of its P6 counterparts:

#!/usr/bin/env perl6
use Compress::Zlib;

sub object-read( $repo, $sha ) {
    my $path = $repo ~ "/objects/" ~ $sha.substr(0, 2) ~ "/" ~
               $sha.substr(2, *);

    given slurp($path, :bin) -> $f {
        my $raw = uncompress($f).decode('utf8-c8'); # Probable error here?!
        return $raw.chars;
    }

}

put object-read(".git", "1372c654fd9bd85617f0f8b949f1405b0bd71ee9")

However, when I run them, they give me back off-by-one results:

$ python bin.py
75
$ perl6 bin.p6
74

Answer 1

@melpomene has hit the spot. You are not decoding in Python, and the number of bytes in the raw file might be a bit more; insert

say uncompress($f).elems;

before decoding to $raw and you will see that it includes (in the file and in my system) 2 bytes more. Rendering via utf8-c8 might merge a couple of bytes into a single codepoint (or more). In general, the number of codepoints will be less than the number of bytes in an IO stream.