1. LF Scheme Interpretter
2. Crux92
LFScheme is a small Scheme interpretter that I
wrote sometime in 1999 when I pondered the idea of having a Lisp-like scripting
language in a game engine. It may seem stupid at first, but at that time a game
project called Golgotha released its source code and that was where I saw a Lisp-
like scripting language used in a game for the first time. Believe me, it didn't
look that bad. Lisp was widely used at M.I.T. during 70s. Scheme is a simple
dialect of Lisp with a small and efficient implementation. The beaty of it is
that a part of the language can be written in itself. Scheme is a totally
different language than, for example, C++. It is forcing you to keep a different
line of thinking. Among other things, I believe it is good for every programmer
to know the principles of other programming languages.
(define fact
lambda (n) (if (= n 0)
1
(* n (fact (- n 1)))))
LFScheme is not complete (concerning its specification as covered in
"Revised(5) Report on the Algorithmic Language Scheme.") It has all that I needed
at the time of its development. The download package is here. It's written in Java. The file "library.scm" is
where you can find what's missing from this implementation (compared with the
document mentioned above). Entries beginning with "TODO" can be implemented in
Scheme and "NO" denotes features requiring changes to the Java code.
One day
I visited a site with tons of games for ZX Spectrum (an
8-bit computer popular in Europe during 80s). It was my first "real" computer on
which I've actually gained my first programming skills. On that site, I've also
found a snapshot of a game I wrote some 12-13 years ago, at the beginning of
90s, at a time when all these machines were being replaced by Amiga, Atari ST,
and even later on by PCs. The game is called Crux 92. You can
grab a snapshot for an emulator here or you
can go
here
and play it on-line. The language is Czech, but you can answer 'N' to all the
initial questions, press '0' to start the game and use
the keys 'O','P','Q','A' to control the vehicle. The goal is to position some
red boxes in the path of those moving robots to force them to run into a mine
and explode. I remember programming the game with just a tape machine, so no
floppy disk or microdrive to store the source code. Everything must have been in
the Z-80 assembler - that's how games were programmed at that time. As I only
had the 48kB version of GENS (an assembler editor and machine code compiler), in
the middle of development I ran out memory which could no more store all the
source code. So the GUI was separated and had to communicate with the game core
via something, which now we'd call an interface, but at that time it was just a
fixed place in the memory with an array of addresses to other procedures
(similar to the library base used in the Amiga OS).
© 2002-5 Marek Trefny
One day
I visited a site with tons of games for ZX Spectrum (an
8-bit computer popular in Europe during 80s). It was my first "real" computer on
which I've actually gained my first programming skills. On that site, I've also
found a snapshot of a game I wrote some 12-13 years ago, at the beginning of
90s, at a time when all these machines were being replaced by Amiga, Atari ST,
and even later on by PCs. The game is called Crux 92. You can
grab a snapshot for an emulator here or you
can go
here
and play it on-line. The language is Czech, but you can answer 'N' to all the
initial questions, press '0' to start the game and use
the keys 'O','P','Q','A' to control the vehicle. The goal is to position some
red boxes in the path of those moving robots to force them to run into a mine
and explode. I remember programming the game with just a tape machine, so no
floppy disk or microdrive to store the source code. Everything must have been in
the Z-80 assembler - that's how games were programmed at that time. As I only
had the 48kB version of GENS (an assembler editor and machine code compiler), in
the middle of development I ran out memory which could no more store all the
source code. So the GUI was separated and had to communicate with the game core
via something, which now we'd call an interface, but at that time it was just a
fixed place in the memory with an array of addresses to other procedures
(similar to the library base used in the Amiga OS).