Most of my hacking cycles right now are going towards debugging the new code generator for GHC. The code generation stage of GHC takes the Spineless Tagless G-machine (STG) intermediate representation (IR) to the C-- high-level assembly representation; the old code generator essentially performed this step in one big bang. The new code generator is [...]
Hoopl is a “higher order optimization library.” Why is it called “higher order?” Because all a user of Hoopl needs to do is write the various bits and pieces of an optimization, and Hoopl will glue it all together, the same way someone using a fold only needs to write the action of the function [...]
And then a signal to the ri-i-i-ight. One notable wart with readline is that if you ^C during the prompt, nothing happens, and if you do a second ^C (and weren’t buggering around with the signal handlers) your entire program unceremoniously terminates. That’s not very nice! Fortunately, readline appears to be one of the rare [...]
About a month ago I decided that it would be cool if I could solve the bug GHC's runtime never terminates unused worker threads. Well, I just got around to looking at it today, and after wandering aimlessly around the twisty maze that is the GHC RTS for an hour or so, I finally found [...]
Last post, I talked about some of the notable difficulties in emulating pthread_cancel on Windows. Today, I want to talk about what a platform agnostic compiler like GHC actually ought to do. Recall our three design goals: GHC would like to be able to put blocking IO calls on a worker thread but cancel them [...]
Edward, I’m afraid I have some bad news. Your interruptible GHC patch; it was involved in a terrible accident on the way to Windows portability. I hope you understand: we’re doing our best to patch it up, but there have been some complications... Pop quiz! What does this pthreads code do? #include <pthread.h> #include <stdio.h> [...]
In my tech talk about abcBridge, one of the “unsolved” problems I had with making FFI code usable as ordinary Haskell code was interrupt handling. Here I describe an experimental solution involving a change to the GHC runtime system as suggested by Simon Marlow. The introductory section may be interesting to practitioners looking for working [...]