Battlesnake is “a competitive game where your code is the controller”. In particular, in answering the question “What is Battlesnake?”, the documentation says:
In this game, each Battlesnake is controlled in real-time by a live web server, responding to the Battlesnake API. It navigates the game board based on your algorithm, trying to find food, avoid other Battlesnakes, and survive as long as possible. Battlesnakes can be built using any tech stack you’d like, and we encourage you to step outside of your comfort zone.
It is also a very neat set of episodes of “Coding Badly” from almost two years ago that talks about building battlesnakes using Factor. In particular, they use a live-coding style to explore the development environment, build web servers using the furnace web framework, and learn how to use and deploy their program!
I did not know about these videos until today, but I thought it makes a nice series to share with the world. I love it when people build things using Factor and am always glad to hear about it!
More information is also available on the @BattlesnakeOfficial GitHub organization, as well as an archive of the Coding Badly implementation and a different Factor battlesnake library by another contributor.
“Life can only be understood backwards; but it must be lived forwards.” — Kierkegaard
I’m very pleased to announce the release of Factor 0.100!
OS/CPU | Windows | Mac OS | Linux |
---|---|---|---|
x86 | 0.100 | 0.100 | |
x86-64 | 0.100 | 0.100 | 0.100 |
Source code: 0.100
This release is brought to you with over 1400 commits by the following individuals:
Aditya Aryaman Das, Alex
null
Maestas, Alexander Ilin, Andy Kluger, Bhargav Shirin Nalamati, Charlie Weismann, Dave Carlton, David Enders, Doug Coleman, Evgenii Petrov, Giftpflanze, Ikko Eltociear Ashimine, J. Ryan Stinnett, Jean-Marc Lugrin, John Benediktsson, Keldan Chapman, Limnanthes Serafini, Marc Michael, Michael Raitzam, Michael Thies, Pragya Pant, Raghu Ranganathan, Rebecca Kelly, Rudi Grinberg, Sandesh Pyakurel, Sebastian Strobl, Shruti Sen, Surav Shrestha, Val Packett, @Capital-EX, @Smoothieewastaken, @TheWitheredStriker, @TryAngle, @chunes3, @inivekin, @nomennescio, @olus2000.
Besides some bug fixes and library improvements, I want to highlight the following changes:
xmlns
that were accidentally changed to https
Some possible backwards compatibility issues:
focusable-child*
now returns f
to indicate parent should be focusedPEG:
and PARTIAL-PEG:
forms, not delay to first invocationmacosx
to macos
deg>rad
and rad>deg
to math.functions vocabularydivisor?
to support mixed numbers (floats and integers)integer-log10
and integer-log2
to math.functions vocabularyhttp.download
vocabularyread-json
returns a single object, use read-jsons
to read multiplebase32-crockford
and base32hex
vocabulariesI would also like to bring particular recognition to Raghu Ranganathan, also known as @razetime, who was an incredible developer with an incredibly good attitude and contributing member to many technical communities including code golfing and various programming languages including Factor. We are very sad that he passed away a couple of months ago and would like to have this moment dedicated in his memory.
Factor is a concatenative, stack-based programming language with high-level features including dynamic types, extensible syntax, macros, and garbage collection. On a practical side, Factor has a full-featured library, supports many different platforms, and has been extensively documented.
The implementation is fully compiled for performance, while still supporting interactive development. Factor applications are portable between all common platforms. Factor can deploy stand-alone applications on all platforms. Full source code for the Factor project is available under a BSD license.
download
wordspromises
tools.image-analyzer
ssize_t
stream-read-c-ptr
and read-c-ptr
assocs.extras
, removed with-assoc
set-of
from assocs
sunrise
, sunset
, and solar-noon
class<=
for anonymous-predicate
contrast-text-color
to select white/black text on dark/light backgroundssequence-case
, fix 3tri*
command-line-options
for easy options parsingcontributors.
and make the changelog respect .mailmap
filenodelay
LIKE" column"
syntaxbad-escape
format-directive
EBNF wordrglob
for recursive glob<t:meta>
tag to be able to specific any meta attributesnths
I"
interpolated string syntax, allow format directives to be usedunder
?move-file
move-file
to properly replace existing filesif-file-exists
combinators and (file-writer-secure)
default-cache-directory
to work in MacPorts environmentsafe-replace-file
and safe-modify-file
<connected-pair>
strip-ansi-escapes
and format-ansi-tables
read-json
to read-jsons
, added read-json
that reads a single object/etc/ld.so.cache
(such as NixOS)setlocale
supportgelu
, stable-softmax
, and stable-log-softmax
binary-bits
tuple<k-permutations>
for k=0squared-euclidian-distance
and normalized-squared-euclidian-distance
, aliases for taxicab-distance
and chessboard-distance
weighted-randoms-as
deg>rad
and rad>deg
), math.functions.integer-logs, and integer-sqrt
, added fma
(fused-multiply-add)<matrix-by>
>digits
and digits>
?read-msgpack
and read-msgpacks
json.http
vocabulary<cheapest-chat-completion>
for ease-of-use with “gpt-4o-mini”, add timestamps to the list-models apimulti-texture
scalingN
for new game a lotqualified-names?
to allow word names to be prettyprinted as fully-qualifiedcompose-all
random-bits*
to random-bits-exact
, rename the *-random-float
distributions to *-random
, add *-distribution
types, added more of them, defined a base-random
that allows a better not-a-random-generator
error to be produced in some casesrand()
is used to generate full range of 32-bit numbersdomain-stats
count=
, faster longest-subseq
lastn
, ?lastn
, set-lastn
get+increment
to consume
, and change next
to return the next elementproduct-each
, product-map
, and product-find
significantly fasterdeep-clone
dupdd
\r\n\v\f\x1c\x1d\x1e\x85\u002028\u002029
macosx
to macos
VOCAB:
syntaxVOCAB:
syntaxclose-all-windows
DISPLAY
os-var for graphical capabilityDISPLAY
os-var for graphical capabilityupdate-command-map
f focusable-child
busy loop~/.factor-history
filekm^2
and more aliasesvocab-exists?
no longer throw bad-vocab-name
<t:meta>
in child templatesuninterned-word
predicate, undefined-word
error classqdoc
and sparql
modeszmq-error
to be an error class2024b
Building a “cash register” is an often used example project, from places like the freeCodeCamp’s Javascript Algorithms and Data Structures Project “Cash Register” or codecademy’s “Building a Cash Register” along with other examples like the Simple Cash Register in Python.
I thought it would be fun to write about building something similar, but not the same, in Factor.
We are going to make a few assumptions:
Here are our units of change along with their descriptions:
CONSTANT: COINS {
{ 10000 "$100" }
{ 5000 "$50" }
{ 2000 "$20" }
{ 1000 "$10" }
{ 500 "$5" }
{ 200 "$2" }
{ 100 "$1" }
{ 25 "quarters" }
{ 10 "dimes" }
{ 5 "nickels" }
{ 1 "pennies" }
}
If we want to make change, we can generate it using something like the greedy algorithm to find minimum number of coins, starting with the largest denomination possible and iterating to smaller ones:
: make-change ( n -- assoc )
COINS [ [ /mod swap ] dip ] assoc-map swap 0 assert= ;
For convenience, we can make a formatting word to format our coins into dollars:
: $. ( n -- )
100 /f "$%.2f\n" printf ;
And now a word to print out the change we made:
: change. ( n -- )
"CHANGE: " write dup $. make-change [
'[ _ "%d of %s\n" printf ] unless-zero
] assoc-each ;
We can store the amount owed and the amount paid in dynamic variables:
INITIALIZED-SYMBOL: owed [ 0 ]
INITIALIZED-SYMBOL: paid [ 0 ]
Using that, we can make a word to display the balance due:
: balance. ( -- )
"OWED: " write owed get-global $.
"PAID: " write paid get-global $. ;
A word to add a charge, increasing the amount owed:
: charge ( n -- )
"CHARGE: " write dup $.
owed [ + ] change-global balance. ;
A word to make a payment, providing change if the amount paid is greater than the amount owed:
: pay ( n -- )
"PAY: " write dup $.
paid [ + ] change-global balance.
paid get-global owed get-global - dup 0 >=
[ change. 0 owed set-global 0 paid set-global ] [ drop ] if ;
And a word to cancel a transaction, refunding any paid amounts:
: cancel ( -- )
"CANCEL" print
0 owed set-global
paid [ change. 0 ] change-global ;
Using a word that parses input into a number of pennies:
: parse-$ ( args -- n )
"$" ?head drop string>number 100 * round >integer ;
We can then define a set of commands using the command-loop vocabulary:
CONSTANT: COMMANDS {
T{ command
{ name "balance" }
{ quot [ drop balance. ] }
{ help "Display current balance." }
{ abbrevs { "b" } } }
T{ command
{ name "charge" }
{ quot [ parse-$ charge ] }
{ help "Charge an item." }
{ abbrevs { "c" } } }
T{ command
{ name "pay" }
{ quot [ parse-$ pay ] }
{ help "Pay with money." }
{ abbrevs { "p" } } }
T{ command
{ name "cancel" }
{ quot [ drop cancel ] }
{ help "Cancel transaction." }
{ abbrevs { "x" } } }
}
And then define the loop that we run as MAIN:
: cash-register-main ( -- )
"Welcome to the Cash Register!" "$>"
command-loop new-command-loop
COMMANDS [ over add-command ] each
run-command-loop ;
MAIN: cash-register-main
And you can see an example from running it:
Welcome to the Cash Register!
$> c 10.23
CHARGE: $10.23
OWED: $10.23
PAID: $0.00
$> c 15.37
CHARGE: $15.37
OWED: $25.60
PAID: $0.00
$> p 100.00
PAY: $100.00
OWED: $25.60
PAID: $100.00
CHANGE: $74.40
1 of $50
1 of $20
2 of $2
1 of quarters
1 of dimes
1 of nickels
It could be fun to extend this example to have an inventory of purchasable items, allow users to ring up these items instead of a series of charges, maybe implement taxable items and discounts, display and print receipts, handle refunds, handle available bills and coins when making change, support other currencies, and other features that you might find in a more “complete” or “real-world” cash register.
The code for this is on my GitHub.
As close as I can tell, Factor is the result of contributions from around 180 contributors over the past 20 years.
Recently, I was reminded of a tool that can produce graphs showing some aspects of contributions to git repositories. The tool is called Git of Theseus written in the Python programming language, which can be used to generate a series of interesting plots showing statistics over time about a project. A similar tool is Hercules, which claims to be a bit faster and is written in the Go programming language.
We can look at code written in each year which, aside from the first few years, mostly continues to exist in the latest version. In addition, we see a healthy and increasing chart over time:
When wondering about the half-life of code, we might want to see how long a particular line of code continues to exist in the project. We can see that 50% of them are still existing after 5 years:
Many of those early contributions came from Slava Pestov, Doug Coleman, Chris Double, and others, and we continue to benefit from the impressive early work that they did for the Factor programming language. We can plot author statistics, and see the large blocks of contributions over time by various authors:
And, as a percentage of lines of code, see that beginning with almost 100% of the source code contributed by Slava Pestov, more recently we have around 20% each from Slava Pestov, Doug Coleman, and myself as well as several other significant authors:
We can generate a more detailed breakdown of these lines of code by language using tokei, but in particular see that we have over 388,000 lines of Factor source code in our latest development version:
$ tokei .
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Language Files Lines Code Comments Blanks
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Factor 4952 503452 388845 25717 88890
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
It was pretty great to generate these graphs, and to reminisce about all the vocabularies available so far, and ponder all those still yet to be written.
Happy coding!
While trying to help get the BitGuessr game deployed on macOS, I ran into a few issues that were interesting, and I wanted to discuss the process of troubleshooting them.
Sometimes, using the deploy
tool
is easy, and sometimes it is not-so-easy. There are some challenges around
choosing the right level of reflection for the features used in the
application you are trying to deploy – we suggest starting with Full environment
and then reducing until the program breaks – but besides that
it is typically one command:
IN: scratchpad "bitguessr" deploy
That command results in a per-platform executable, which on
macOS is an .app
bundle that includes the
Factor executable, a deployed image, any resources the deployed image uses, and
any libraries that the deployed image depends on:
$ find bitguessr.app
bitguessr.app
bitguessr.app/Contents
bitguessr.app/Contents/Frameworks
bitguessr.app/Contents/Frameworks/libraylib.dylib
bitguessr.app/Contents/Info.plist
bitguessr.app/Contents/MacOS
bitguessr.app/Contents/MacOS/bitguessr
bitguessr.app/Contents/Resources
bitguessr.app/Contents/Resources/bitguessr
bitguessr.app/Contents/Resources/bitguessr/_resources
bitguessr.app/Contents/Resources/bitguessr/_resources/bitguessr_icon.png
bitguessr.app/Contents/Resources/bitguessr/_resources/bitguessr_soundtrack.wav
bitguessr.app/Contents/Resources/bitguessr/_resources/button-0.png
bitguessr.app/Contents/Resources/bitguessr/_resources/button-1.png
bitguessr.app/Contents/Resources/bitguessr/_resources/correct.wav
bitguessr.app/Contents/Resources/bitguessr/_resources/wrong.wav
bitguessr.app/Contents/Resources/bitguessr.image
bitguessr.app/Contents/Resources/Icon.icns
After building this application, checking that it works for me, and uploading it to the server, of course we got a bug report when someone else tried to run it:
$ ./bitguessr.app/Contents/MacOS/bitguessr
...
Cannot resolve C library function
Library: DLL" libraylib.dylib"
Symbol: InitWindow
DlError: none
See https://concatenative.org/wiki/view/Factor/Requirements
Is the InitWindow
symbol in the library?
$ nm -gU ./bitguessr.app/Contents/Frameworks/libraylib.dylib | grep InitWindow
0000000000017920 T _InitWindow
Yes, it is.
Is it loading the correct libraylib.dylib
file?
$ DYLD_PRINT_LIBRARIES=1 ./bitguessr.app/Contents/MacOS/bitguessr
...
dyld[69951]: <B5534AF8-58E9-3F59-A5DE-F33164570F6B> ./bitguessr.app/Contents/Frameworks/libraylib.dylib
Yes, it seems to be.
Let’s learn more about how dynamic libraries work. There is a nice thread on dynamic library identification that goes into some details about how these are identified and then loaded.
Let’s start with the library – we get our Raylib from Homebrew:
$ cd $(brew --prefix raylib)
$ otool -l libraylib.dylib | grep -A 2 LC_ID_DYLIB
cmd LC_ID_DYLIB
cmdsize 72
name /usr/local/opt/raylib/lib/libraylib.450.dylib (offset 24)
Okay, so this probably needs to be relative to a “runtime path” or rpath
,
which you can either set:
$ install_name_tool -id "@rpath/libraylib.dylib" libraylib.dylib
Or, fix by downloading a Raylib release that is already set properly for embedding.
Did it change?
$ otool -l libraylib.dylib | grep -A 2 LC_ID_DYLIB
cmd LC_ID_DYLIB
cmdsize 48
name @rpath/libraylib.dylib (offset 24)
Yes, it did!
Now that we have that, we can re-deploy and see if it works:
$ ./bitguessr.app/Contents/MacOS/bitguessr
...
Cannot resolve C library function
Library: DLL" libraylib.dylib"
Symbol: InitWindow
DlError: none
See https://concatenative.org/wiki/view/Factor/Requirements
Nope.
Okay, maybe the rpath
that is used to lookup dynamic libraries isn’t set
properly:
$ otool -l ./bitguessr.app/Contents/MacOS/bitguessr| grep -A 2 LC_RPATH
Hmm, it is not set at all. The dynamic linker maintains a list of these “runtime path” directories. Maybe we can make sure it looks in the right place by adding one:
$ cd ./bitguessr.app/Contents/MacOS
$ install_name_tool -add_rpath "@executable_path/../Frameworks" bitguessr
Okay, now it looks right:
$ otool -l ./bitguessr.app/Contents/MacOS/bitguessr | grep -A 2 LC_RPATH
cmd LC_RPATH
cmdsize 48
path @executable_path/../Frameworks (offset 12)
Let’s try again… and, it works!
I pushed a change to set the rpath
directory
properly for future deploys, changed to distributing it as an Apple Disk
image, and also made sure to
codesign the
application
so that it launches easily after being downloaded and gave Joseph
Oziel an updated macOS build of
BitGuessr which included an
Icons.icns
file in the Apple Icon Image
format for the
application icon.
Neat!
I have been quite distracted by Rosetta Code shenanigans in the past few days. For anyone that is curious about the backstory, I removed the rosetta-code vocabulary from the main Factor git repository, and then decided to archive all the Factor solutions to a separate factor-rosetta-code repository for posterity, utility, and analysis.
I thought it would be fun to talk about different ways to do web scraping for the Rosetta Code website, ultimately choosing to write a Factor vocabulary to do it, which I’ll go into below.
There are a couple public datasets and scraper tools that you can use:
I started with the previous approaches, but then I realized that I kinda wanted to build my own program that only grabbed the Factor solutions and weaved them into solution files with the task description for the factor-rosetta-code repository.
After considering using the rendered HTML
from the Rosetta Code website, I decided it would be
a lot simpler to use the MediaWiki API
and our mediawiki.api
vocabulary to
extract the tasks. That vocabulary requires an endpoint
to be specified, so
we define a simple combinator that sets it before running a
quotation.
: with-rosetta-code ( quot -- )
[ "https://rosettacode.org/w/api.php" endpoint ] dip
with-variable ; inline
The Rosetta Code
solutions
consists of a list of pages as well as sub-categories with their own lists of
pages. We need a list-category
word that will get the members of a given
category, memoized
in case pages reference each other or to speed up subsequent calls through
caching:
MEMO: list-category ( title -- members )
'H{ { "list" "categorymembers" } { "cmtitle" _ } }
query [ "title" of ] map ;
And a list-categories
word that will recursively resolve categories
containing other categories:
: list-categories ( title -- tasks )
list-category [ "Category:" head? ] partition swap
[ list-categories ] map concat append harvest members sort ;
Using these, we can retrieve all tasks and draft tasks:
: all-tasks ( -- tasks )
"Category:Solutions_by_Programming_Task" list-categories ;
: draft-tasks ( -- tasks )
"Category:Draft_Programming_Tasks" list-categories ;
Each task page is a series of sections, beginning with the task description, and then a series of solutions in different programming languages. Using page-content, we can see what one of these pages looks like:
IN: scratchpad [ "Sieve_of_Eratosthenes" page-content ] with-rosetta-code
We can build a word that extracts a section that is specified by a begin
text and an end
text, searching for them using
subseq-index
to find where they occur in the page:
:: extract-section ( page begin end -- section/f )
page begin subseq-index [
begin length +
dup page end subseq-index-from
[ page length ] unless*
page subseq
] [ f ] if* ;
The description is everything before the first header section:
: get-description ( page -- description/f )
"=={{header" over subseq? [
"" "=={{header" extract-section
] [ drop f ] if ;
The solution code is the first <syntaxhighlight>
block for our desired
language:
: get-code ( page lang -- code/f )
"<syntaxhighlight lang=\"" "\">" surround
"</syntaxhighlight>" extract-section ;
We can use those words to weave the commented-out description with the Factor source code:
: get-solution ( task -- solution/f )
page-content [ get-description ] keep over empty?
[ 2drop f ] [
[ string-lines [ "! " prepend ] map "\n" join ]
[ "factor" get-code "\n\n" glue "\n" append ] bi*
] if ;
That works great, you can try it by printing out one of the draft tasks:
IN: scratchpad [ "10001th_prime" get-solution print ] with-rosetta-code
! Task:
!
! Find and show on this page the 10001st prime number.
USING: math math.primes prettyprint ;
2 10,000 [ next-prime ] times .
Now we want a way to save a task, and since the tasks have names that aren’t all valid in filenames or vocabulary names, we do a little cleanup to turn a task name into a path:
: task-path ( task -- path )
[ dup { [ Letter? ] [ digit? ] } 1|| [ drop CHAR: - ] unless ] map
>lower R/ --+/ "-" re-replace [ CHAR: - = ] trim ".factor" append ;
Saving a task is getting the solution and then saving to a file:
: save-task ( task -- )
"vocab:rosetta-code/solutions" [
[ get-solution ]
[ task-path '[ _ utf8 set-file-contents ] when* ] bi
] with-directory ;
With that, we can finally save all the tasks, or all the draft tasks:
: save-all-tasks ( -- )
all-tasks [ save-task ] each ;
: save-draft-tasks ( -- )
draft-tasks [ save-task ] each ;
I used this, with some minor changes to ignore certain categories that do not contain solutions, as well as using Pandoc to convert the MediaWiki markup before embedding in the solution files.
Anyway, pretty cool!
I recently wrote about removing the Rosetta Code solutions from our main Factor repository. We only had 62 solutions out of 1,276 tasks, and I didn’t really want to maintain a subset of the solutions, nor mirror them ineffectively into the main git repository.
As it turns out – and pretty much immediately afterwards – I got curious enough to try and download all of the Factor solutions so we could maybe do some analysis of all the various solutions that have been contributed to the Rosetta Code project. And, it’s not a small amount of code – it’s 12,461 lines of Factor code!
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Language Files Lines Code Comments Blanks
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Factor 1663 74221 12461 55885 5875
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Not all of those are fully solved, but almost 1,000 of them seem to be!
This is available in the newly created factor-rosetta-code git repository, if anyone else is as curious as I was. I don’t think we are going to be able to consistently keep this in sync with the Rosetta Code website, but at least it represents a checkpoint today for quite a lot of nice Factor source code.
Some of these were written for older versions of Factor, but most of it is usable as is, or with minor edits.
Check it out!
planet-factor is an Atom/RSS aggregator that collects the contents of Factor-related blogs. It is inspired by Planet Lisp.