# Postdoc position in Ljubljana

A postdoc position in the Effmath research project is available at the University of Ljubljana, Faculty of Mathematics and Physics. The precise topic is flexible, but should generally be aligned with the project (see project description). Possible topics include:

•  reasoning about computational effects
•  implementation of computational effects
• proof assistants and formalization of mathematics

The candidate should have a PhD degree in mathematics or computer science, with background knowledge relevant to the project area. The position is available for a period of one year with possibility of extension, preferably starting in early 2016. No knowledge of the Slovene language is required.

The candidates should contact Andrej Bauer by email as soon as possible, but no later than January 8th 2016. Please include a short CV and a statement of interest.

# The HoTT book

The HoTT book is finished!

Since spring, and even before that, I have participated in a great collaborative effort on writing a book on Homotopy Type Theory. It is finally finished and ready for public consumption. You can get the book freely at http://homotopytypetheory.org/book/. Mike Shulman has written about the contents of the book, so I am not going to repeat that here. Instead, I would like to comment on the socio-technological aspects of making the book, and in particular about what we learned from open-source community about collaborative research.

# A hott thesis

Egbert Rijke successfully defended his master thesis in Utrecht a couple of weeks ago. He published it on the Homotopy type theory blog (here is a direct link to the PDF file (revised)). The thesis is well written and it contains several new results, but most importantly, it is a gentle yet non-trivial introduction to homotopy type theory. If you are interested in the topic but do not know where to start, Egbert’s thesis might be perfect for you. As far as I know it is the first substantial piece of text written in (informal) homotopy type theory.

What I find most amazing about the work is that Egbert does not have to pretend to be a homotopy type theorist, like us old folks. His first contact with type theory was homotopy type theory, which impressed on his mind a new kind of geometric intuition about $\Pi$’s, $\Sigma$’s and $\mathrm{Id}$’s. If we perform enough such experiments on young bright students, strange things will happen.

# Eff 3.0

Matija and I are pleased to announce a new major release of the eff programming language.

In the last year or so eff has matured considerably:

• It now looks and feels like OCaml, so you won’t have to learn yet another syntax.
• It has static typing with parametric polymorphism and type inference.
• Eff now clearly separates three basic concepts: effect types, effect instances, and handlers.
• How eff works is explained in our paper on Programming with Algebraic Effects and Handlers.
• We moved the source code to GitHub, so go ahead and fork it!

# Bob Harper has a blog

Bob Harper of CMU, has recently started a blog, called Existential Type, about programming languages. He is a leading expert in Programming Languages. I remember being deeply inspired the first time I heard him talk. I was an incoming graduate student at CMU and he presented what the programming languages people at CMU did. His posts are fun to read, unreserved and very educational. Highly recommended!