Reading Camlp4, part 3: quotations in depth
(I set myself the goal of posting every week, but the latest Skydeck release has kept me busy, and it turned out I didn't understand the following as well as I thought.)After seeing the examples of...
View ArticleReading Camlp4, part 4: consuming OCaml ASTs
It's easy to think of Camlp4 as just "defmacro on steroids"; that is, just a tool for syntax extension, but it is really a box of independently-useful tools. As we've seen, Camlp4 can be used purely...
View ArticleEqueue compared to Lwt
I feel like taking a break from Camlp4, so in this post I'll take a look at two libraries for asynchronous networking programming in OCaml: Equeue and Lwt. Each provides cooperative multithreading and...
View ArticleMonadic functional reactive AJAX in OCaml
Yesterday I released three related projects which I've been working on for a long time: ocamljs, a Javascript backend for ocamlc, along with some libraries for web programmingorpc, a tool for...
View ArticleSudoku in ocamljs, part 1: DOM programming
Let's make a Sudoku game with ocamljs and the Dom library for programming the browser DOM. Like on the cooking shows, I have prepared the dish we're about to make beforehand; why don't you taste it...
View ArticleSudoku in ocamljs, part 2: RPC over HTTP
Last time we made a simple user interface for Sudoku with the Dom module of ocamljs. It isn't a very fun game though since there are no pre-filled numbers to constrain the board. So let's add a button...
View ArticleSudoku in ocamljs, part 3: functional reactive programming
In part 1 and part 2 of this series, we made a simple Sudoku game and connected it to a game server. In this final installment I want to revisit how we check that a board satisfies the Sudoku rules....
View ArticleLwt and Concurrent ML
Programming concurrent systems with threads and locks is famously, even fabulously, error-prone. With Lwt's cooperative threads you don't have to worry so much about protecting data structures against...
View ArticleReading Camlp4, part 5: filters
Hey, long time no see!It is high time to get back to Camlp4, so I would like to pick up the thread by covering Camlp4 filters. We have previously considered the parsing and pretty-printing facilities...
View ArticleInside OCaml objects
In the ocamljs project I wanted to implement the OCaml object system in a way that is interoperable with Javascript objects. Mainly I wanted to be able to call Javascript methods with the OCaml method...
View ArticleUpdated backtrace patch
I’ve updated my backtracepatch to work with OCaml 3.11.x as well as 3.10.x. The patch providesaccess to backtraces from within a program (this is already provided in stock 3.11.x)backtraces for...
View Articleorpc 0.3
I am happy to announce version 0.3 of orpc, a tool for generating RPC bindings from OCaml signatures. Orpc can generate ONC RPC stubs for use with Ocamlnet (in place of ocamlrpcgen), and it can also...
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How froc works
.post img { border: none; } I am happy to announce the release of version 0.2 of the froc library for functional reactive programming in OCaml. There are a number of improvements:better event model:...
View ArticleReading Camlp4, part 6: parsing
In this post I want to discuss Camlp4’s stream parsers and grammars. Since the OCaml parsers in Camlp4 (which we touched on previously) use them, it’s necessary to understand them in order to write...
View ArticleReading Camlp4, part 7: revised syntax
As we have seen, Camlp4 contains an alternative syntax for OCaml, the “revised” syntax, which attempts to correct some infelicities of the original syntax, and to make it easier to parse and...
View ArticleReading Camlp4, part 8: implementing quotations
The Camlp4 system of quotations and antiquotations is an awesome tool for producing and consuming OCaml ASTs. In this post (and the following one) we will see how to provide this facility for other...
View ArticleReading Camlp4, part 9: implementing antiquotations
In this post I want to complicate the JSON quotation library from the previous post by adding antiquotations.AST with antiquotationsIn order to support antiquotations we will need to make some changes...
View ArticleReading Camlp4, part 10: custom lexers
As a final modification to our running JSON quotation example, I want to repair a problem noted in the first post—that the default lexer does not match the JSON spec—and in doing so demonstrate the use...
View ArticleMixing monadic and direct-style code with delimited continuations
The Lwt library is a really nice way to write concurrent programs. A big downside, however, is that you can’t use direct-style libraries with it. Suppose we’re writing an XMPP server, and we want to...
View Articleocamljs 0.3
I am happy to announce version 0.3 of ocamljs. Ocamljs is a system for compiling OCaml to Javascript. It includes a Javascript back-end for the OCaml compiler, as well as several support libraries,...
View ArticleReading Camlp4, part 11: syntax extensions
In this final (?) post in my series on Camlp4, I want at last to cover syntax extensions. A nontrivial syntax extension involves almost all the topics we have previously covered, so it seems fitting...
View ArticleThree uses for a binary heap
Lately I have been interviewing for jobs, so doing a lot of whiteboard programming, and binary heaps keep arising in the solutions to these interview problems. There is nothing new or remarkable about...
View ArticleLogic programming in Scala, part 1
I got a new job where I am hacking some Scala. I thought I would learn something by translating some functional code into Scala, and a friend had recently pointed me to Kiselyov et al.’s Backtracking,...
View ArticleLogic programming in Scala, part 2: backtracking
In the previous post we saw how to write computations in a logic monad, where a “value” is a choice among alternatives, and operating on a value means operating on all the alternatives.Our first...
View ArticleLogic programming in Scala, part 3: unification and state
In this post I want to build on the backtracking logic monad we covered last time by adding unification, yielding an embedded DSL for Prolog-style logic programming.PrologHere is a small Prolog...
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