Hashing a Tree: Glacier hashes, FP, and Perl

Hashing a Tree: Glacier hashes, FP, and Perl

By Steven Lembark (‎Lembark‎) from stlouis.pm
Date: Tuesday, 21 June 2016 11:00
Duration: 50 minutes
Target audience: Any
Language: English
Tags: aws functional glacier hash keyword::declare perl5 perl6 programming recursion tail tree

You can find more information on the speaker's site:

Amazon's "Glacier" service is designed for long-term storage of large, cold data. To support really large uploads, Glacier uses multipart uploads, with 1MiB chunks. Glacier's Tree Hash algorithm uses a hash-of-hashes approach to give a consistent way of hashing both single- and multi-part uploads.

This talk describes a Functinal Programming approach to generating the hashes, starting with a traditional for-loop and progressing through using constant data and tail recursion to get a fast, simple FP solution in Perl5.

The original full talk is available at:

The slides used by Dr. Conway and myself for the presentation are at:


Attended by: David H. Adler (‎dha‎), James E Keenan (‎kid51‎), Brett Estrade (‎estrabd‎), Josh Lavin (‎digory‎), brian carlson, Julian Brown,