thirteen-letters VS JITWatch

Note that Common Lisp doesn’t require functional programming. Mutation, side effects, etc. are fine. I just write imperative code for the most part.

My code was quick and dirty, so I don’t think anyone will learn anything from it, but it’s here: https://github.com/jaredkrinke/thirteen-letters

Thirteen Letters is a web-based, competitive word scramble game I made for the Lisp Game Jam (Spring 2023) [0].

The gameplay isn't novel, but it's a multiplayer browser game that's written in 100% Common Lisp (cf. the source code [1]). The front end uses Parenscript, Spinneret, and cl-css to translate s-expressions to JavaScript, HTML, and CSS, respectively. The back end is built using the Hunchentoot web server, Hunchensocket for WebSockets, and yason for JSON, running on SBCL.

I'm fairly new to Common Lisp, so I'm not qualified to dispense advice, but I found having a REPL on the live service to be convenient for monitoring activity, toggling settings, and fixing minor bugs on the fly. It's a lot of fun for hobby projects, although I'd be much more cautious with anything important--I definitely broke the live service a few times by not being careful! I posted a more thorough braindump elsewhere [2].

Let me know what you think! I'm happy to answer any questions. I'll play for a while, to hopefully give people a moderately worth opponent :)

[0] https://itch.io/jam/spring-lisp-game-jam-2023/rate/2103016

[1] https://github.com/jaredkrinke/thirteen-letters

[2] https://log.schemescape.com/posts/game-development/lisp-game...

You can kind of do the same as DISASSEMBLE in Clojure.

There are some helper projects like https://github.com/Bronsa/tools.decompiler, and on the OpenJDK JitWatch (https://github.com/AdoptOpenJDK/jitwatch), other JVMs have similar tools as well.

It isn't as straightforward as in Lisp, but it is nonetheless doable.

As you have encapsulated the asserts inside methods, these will be called at runtime with the arguments evaluated (for example, creating that lambda). When assertions are disabled, the C1/C2 may inline the empty method call eventually, but I don't know whether it drops the lambda instantiation as well. You can use JITWatch to see what gets inlined. The general notion though is to not worry too much. Lazy log messages are a common pattern.

You can use jitwatch for this. To see the actual assembly code generated you will also need to use a debug build of the jvm.

If you use Oracle's own IDE, it will support it out of the box, as it already did on Sun's days.

Then there are other ways depending on which JVM implementation is used.

On OpenJDK's case you can load runtime plugin to do it

https://github.com/AdoptOpenJDK/jitwatch

We use https://github.com/AdoptOpenJDK/jitwatch for this.

If you already know any JVM or .NET language, the first step would be to understand the full stack, you don't need C for that.

Many of us were doing systems programming with other languages before C went mainstream.

What you need to learn is computer architecture.

Getting back to JVM or .NET, you can get hold of JIT Watch, VS debug mode or play online in SharpLab.

Get to understand how some code gets translated into MSIL/JVM, and how those bytecodes end up being converted into machine code.

https://github.com/AdoptOpenJDK/jitwatch/wiki/Screenshots

https://sharplab.io/

Languages like F# and C# allow you to leave the high level comfort and also do most of the stuff you would be doing in C.

Or just pick D, which provides the same comfort and goes even further in low level capabilities.

Use them to write a toy compiler, userspace driver, talking to GPIO pins in a PI, manipulating B-Tree data stuctures directly from inodes, a TCP/IP userspace driver.

Not advocating not to learn Zig, do it still, the more languages one learns the better.

Only advocating what might be an easier transition path into learning about systems programming concepts.

You can enable a lot of debug information about how the compiler decides what to do with your code using feature flags like -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlining. If you want to dive deeper into the world of the Hotspot JIT Compiler, have a look at JITWatch.

In what concerns HotSpot, one way would be JITWatch.