Lisp links thread

[teamonkey]

Shame it's somewhat spoiled by the crappy VNC connection (why is he doing it over VNC?) and other technical problems, but it still gets across the magic of interactively changing a program while it's still running. That's something a lot of programmers can't see what the fuss is about until they actually experience it for themselves.

Being able to change things on the fly is so utterly, utterly valuable for game systems programming too, especially for prototyping and in the early stages of design.

[GoatFoam]

Not strictly lisp

but I have been having a play with OCaml recently. I can't say it has my favourite syntax, but unlike most functional languages it seems quick enough for number crunching.

My first bit of code - a runge kutta integrator. If you think it looks nasty then it is as nothing compared to my C version...

Code: Select all

let rk4_slope(f, t, y, h) =
    let k1 = f(t, y) in
    let h2 = h *. 0.5 in
    let k2 = f((t +. h2), (y +. (h2 *. k1))) in
    let k3 = f((t +. h2), (y +. (h2 *. k2))) in
    let k4 = f((t +. h),  (y +. (h *. k3))) in
    let slope = (((k1 +. k4) +. (2.0 *. (k2 +. k3))) /. 6.0) in
    slope;;

(* f = dy/dt,  h = step size *)
let rk4(f, t, y, h) =
    let slope = rk4_slope(f, t, y, h) in
    y +. (slope *. h);;

[teamonkey]

If you think it looks nasty then it is as nothing compared to my C version...

Lovely and clean, it's practically the maths written straight down. You should see the integrators I had to do in F90.

[GoatFoam]

The less said about f90 the better '-)

Since posting that I have written a vector version, which is a bit uglier but still considerably nicer than my old code. Goes almost as fast too

[adam]

http://schemepy.thousandparsec.net/

embedding a scheme interpreter in a python program

[adam]

one of nebogos things... looks interesting, visual programming for scheme http://www.pawfal.org/index.php?page=SchemeBricks

[teamonkey]

http://www.ventonegro.org/2009/10/schem ... app-store/

Iphone app store game written (mostly) in Gambit Scheme.

[failrate]

Yeah, Gambit's got that Scheme-to-C compiler, innit? I always find that funny, since LISP is already so incredibly close to being a parse-tree that it seems to me that converting it to C is a step backwards. I've tried nosing around with gcc to see how hard it is to write a language front-end... and, well, it's really hard. Maybe that's the allure?

[teamonkey]

C is a portable assembler

[GoatFoam]

Exactly.

Every platform worth targeting already has an ANSI C compiler, and many of them have very good ones.

Why waste time maintaining dozens of platforms when other people have already done the hard work?

[failrate]

Anyone fluent in Japanese?

LISP Manga
http://lambda.bugyo.tk/cdr/mwl/

[Narrengoat]

JScheme (http://jscheme.sourceforge.net/)is worth mentioning. Used it inside a java-based neural network simulator I wrote for a (massively unsuccessful) MSc project. It was useful for quickly generating variations on different network topologies and for interactive debugging and exploring. Just having a repl I could use to pootle about with java objects was invaluable.

[teamonkey]

Another iphone game (WIP) in Gambit Scheme.

http://jlongster.com/blog/2010/02/03/ip ... me-update/

[failrate]

Arc Scheme interpreter in JavaScript: http://jonathan.tang.name/files/arclite/

[teamonkey]

God wrote it in Lisp