Lambda the Ultimate

Internet servers are good applications for scripting, e.g. VCL for the Varnish HTTP cache.

Now there's again talk about using Lua for Apache configuration.

Choice quote:

Can all be done in plain lua.

Given that there's MetaLua, it might even be possible to create Apache-specific syntax.

(via Hacker News)

I've been having trouble finding papers on giving a categorical semantics to F or F_\omega. I know the book "Categorical Logic and Type Theory" gets into this material a bit, but I'm presuming there's been papers on the subject that I'm just entirely ignorant of. Does anyone have pointers?

Cheers,

L-systems are parallel grammars that provide a theoretical foundation for a class of programs used in the simulation of plant development and procedural image synthesis. In particular, the formalism of L-systems guides the construction of declarative languages for specifying input to these programs. We outline key factors that have motivated the development of L-system-based languages in the past, and introduce a new language, L+C, that addresses the shortcomings of its predecessors. We also describe a simulation program, lpfg, which makes it possible to execute models specified in L+C. To this end, L+C programs are translated into C++, compiled into a DLL, and linked with lpfg at runtime. The use of this strategy simplifies the implementation of the modeling system.

I somehow failed to notice L+C as a demarcated language before. I am not entirely sure what one needs to download in order to use L+C directly.

I am sure this is relevant to the great DSL debate, but I am not sure in favor of which side of the debate...

The page gives links to other papers about L+C. While you are there, don't miss The Algorithmic Beauty of Plants, which is great fun.

Disclaimers: i'm struggling to grok half of the words in the paper, so it might not be as interesting as i think it is. I searched but didn't find it explicitly mentioned before on LtU.

The abstract of the paper says:

We recast dataflow in a modern categorical light using profunctors as a generalisation of relations. The well known causal anomalies associated with relational semantics of indeterminate dataflow are avoided, but still we preserve much of the intuitions of a relational model. The development fits with the view of categories of models for concurrency and the general treatment of bisimulation they provide. In particular it fits with the recent categorical formulation of feedback using traced monoidal categories. The payoffs are: (1) explicit relations to existing models and semantics, especially the usual axioms of monotone IO automata are read off from the definition of profunctors, (2) a new definition of bisimulation for dataflow, the proof of the congruence of which benefits from the preservation properties associated with open maps and (3) a treatment of higher-order dataflow
as a biproduct, essentially by following the geometry of interaction programme.