Weekly Review - Week 16

Posted on April 24, 2017

This post is a summary of links related to coding and software I followed and read (sometimes, skimmed over) in the past week. Its purpose is both to serve as a high-level personal log and as a potential source of interesting (or not so interesting) links. Entries are provided in no particular order with minimal comments…

2017-04-17 Monday

The Teeny Tiny Mansion

A formally proved adventure game: There is no dead end in the game, every states has a path that leads to a winning state.

The CBMC Homepage

The model checker that is used by tttm. What’s interesting is that it works directly on C/C++ source files. Could probably be adapted to work on Java files, if this is not already done…

Is there library support for FOL or propositional logic? - Google Groups

Some discussion on the idris-lang mailing about adding native First-Order Logic support in the language

2017-04-18 Tuesday

Enquête sur les modes d’existence

(in French) Criticism of Latour’s book and more generally Latour’s philosophy. Interesting counterpoint while I am trying to use Latour’s concepts to better understand software and our relationship with it.

Le réalisme kitsch | Zilsel

(in French) Another criticism, this time of Object-Oriented Ontology and Speculative Realism

CSS TDD - Review

Is it possible, and useful, to write CSS in TDD mode, with automated tests? Not sure this post provides a positive answer…

2017-04-19 Wednesday

Types + Properties = Software: designing with types

Relinking to a classical series of post on Type-Driven Development in F#.

LeanDevBalleBalle.pdf

Short description of Lean Development as a complement to Lean Manufacturing, by one of the foremost French expert on Lean

Org layer

How to use org-mode in Spacemacs. As I do a lot of pairing in Spacemacs those days, I need to beef up my skills with this environment and retarget my muscles memory to new keystrokes sequences…

abailly/yak-o-matic: visualize your yaks

Thinking of reviving this old project, written with Willem van den Ende at Agile Open France 2013, whose purpose was visualising a dependency graph of tasks given an org-mode file.

2017-04-20 Thursday

Lost in Technopolis

Some fascinating note on the use of category theory as an abstract assembly language to generate equations that are fed to Z3 theorem prover.

encryption - How do I compute the approximate entropy of a bit string? - Stack Overflow

I have been working at the end of the week on a small coding challenge: Write a script that emulates the behavior of cat /dev/random, e.g. that generates an infinite stream of as-random-an-possible bytes. My first thought was : How do I test the randomness of a stream of bytes, and this started some research on the web on how to compute entropy of a string

Salsa20

I chose to use this stream cipher algorithm to generate my stream of random bytes, encryting a stream of bytes coming from a network card put in promiscuous mode. It is reasonably straightforward to understand and implement and generates good “randomness”

RS14.pdf

An article from Ron Rivest describing Spritz, an alternative to RC4.

2017-04-21 Friday

Entropy and Random Number Generators @ Calomel.org

Helpful post on how to compute “entropy” for random generators. Link to the Ent tool

Haskell for all: Use Haskell for shell scripting

I of course chose to write my random generation script in Haskell, trying to use as few dependencies as possible: I managed to get it working using only what’s provided by GHC 8.0.2 distribution. Here is an alternative and more expressive way of writing scripts in Haskell.

2017-04-22 Saturday

Salsa Reference Implemention

Reference implementation of Salsa algorithm in plain old C. salsafamily-20071225.pdf provides more details and rationale on this family of algorithms. This lead me to more stuff on PRNGs and how to gather entropy from the system:

Announcing the AWS Chatbot Challenge – Create Conversational, Intelligent Chatbots using Amazon Lex and AWS Lambda | AWS Blog

Something definitely fun I would love to work on!

2017-04-23 Sunday

A haskell implementation of a pseudo-random number generator using Salsa20 algorithm

Final implementation of my pseudo-random bytes generator in Haskell

Shannon Entropy

I started to use compression ratio as a proxy for entropy of a finite stream of bytes but replaced it with direct measurement of Shannon’s entropy, using the standard formula to compute the number of bits needed to represent all elements of a finite stream X with probability of occurence for each letter of pi.

ARM Releases Machine Readable Architecture Specification – Alastair Reid – Researcher at ARM Ltd

Another fascinating post on the use of formal specifications, this time in the realm of hardware architecture.

Forget about project planning; it just doesn’t work | Alex Katsanos | Pulse | LinkedIn

Looks like waterfall does not very well in “traditional” engineering either…

Testing Theories of American Politics

Can we empirically demonstrate how policies are formed and driven? This article shows the answer is yes by testing actual decisions against theories of whose interest these decisions serve. Would definitely be interested in a similar study for Europe…