Docker Image for SML/NJ

The various Linux distros package repos carry very outdated versions of the SML/NJ compiler. This Docker image builds the latest official SML/NJ release.

Save bits, save power, save the world, Part 2

The GHC Haskell and OCaml compilers do not have builtin popcount support, so again I precomputed the bit pop count for each ASCII letter. Using the same ~9 Mb 4x concatenation of /usr/share/dict/words from last time I measured the performance of the resultant code. This time, the test machine was a Macbook Pro 2.16 GHz with 2 Gb of RAM. The microprocessor is a Core Duo T7400 which has no support for the popcnt instruction anyway.

Substructural Type Systems and Performance, Part 1

Why is the name of this blog "substructural"? In turns out that in the realm of advanced type systems, there is a family of type systems derived from a family of logical systems called substructural logics. The chief distinction of substructural type systems is that one or more of the "structural properties" of type environments are eliminated. These rules are exchange, weakening, and contraction. Exchange allows arbitrarily reordering bindings in the type environment. Weakening enables adding new bindings. A type derivation is deemed "weakened" in the sense that if a program already typechecks using a certain type environment, adding new bindings to that environment won't negate the well-typing of the program.

Firestorm

The past few days have seen a veritable firestorm of flames between the Java and Scala communities. The proximate cause was a leaked private email outlining what the Yammer folks disliked about Scala. An official post from Yammer followed but not before many bloggers had a field day with the leaked email. What is interesting is that one such discussion on Stephen Colebourne's blog pointed that the the lack of a "module system" is a principal deficiency of Scala. This point, mind you, was not part of the Yammer email. In fact, it preceded the email by a few days. The post cited the Scala's community's response to an inquiry about Scala and "module systems" [Google Groups]. That inquiry initially resulted in some misunderstanding.

Programming Language Gotchas

Looks like I spoke too soon. The October rally was looking a little long in tooth, and a little warning from the credit agencies was enough to get the market to go risk off at least for this afternoon. At least yields did not decline too much (2.01% for the 10-year according to MarketWatch). The Dollar Index (DX), however, has certainly been in an uptrend since the end of October trough.

Coming from the Standard ML world of languages makes me take many things for granted. It also gives me a probably pretty narrow perspective. Hacking on my trading analysis tools in other languages helps me broaden that somewhat, though I have certainly worked in the mainstream languages long before I encountered ML and its brethren. I would like to keep a record of these gotchas as I encounter them. I do not intend this as value judgments but rather a documentation of noteworthy differences from a higher-order typed programming language perspective.