Colortest

A series of tiny, non-interactive programs written in various languages that all output a specific, strictly-defined pattern of ANSI escape codes and whitespace to create a 256-color test pattern, and generate it following a specific procedure.

Each program is entirely my original work unless otherwise noted. My understanding and comfort with the languages I've used varies greatly.

Languages

At the current moment, I've implemented it in the following languages:

• AWK
• Algol 68
• Babalang (an esoteric programming language inspired by the puzzle game Baba is you. The specification is here and the official interpreter is available here
• Befunge
• Brainfuck
• C
• C#
• C++
• Cobol
• D
• DC (desk calculator - a very early UNIX stack-based RPN calculator that predates C. Works in the GNU implementation, but not portable to some other implementations. Described by the Esolangs wiki as "the esoteric language that 'made it big'", presumably due to its obscure syntax.)
• Elixir
• Erlang (via Escript)
• Fender (a language created by 3 of my fellow Champlain College students in my senior year, available here)
• Forth
• Fortran
• Go
• Haskell
• Java
• JavaScript (via Node.js)
• jq (a domain-specific language for dealing with JSON data)
• Kotlin
• Lisp (Common Lisp)
• Lua
• Nim
• Objecive-C
• Odin
• OCaml
• Octave (the GNU project's MATLAB-like analytical language)
• Pascal (via FreePascal) (in memory of Niklaus Wirth)
• Perl
• PHP
• PowerShell
• Python
• R
• Rockstar (Version 1, via satriani - an esoteric programming language based on 80s metal and power ballads. Specification and reference implementation are here, but you'll need to check out an older commit for version 1)
• Ruby
• Rust
• Scala
• Scheme
• Shell Script (should work in any POSIX shell)
• TypeScript (just the JavaScript implementation with type annotations and let instead of var) (via ts-node)
• Vala
• x86_64 assembly (NASM Intel-style syntax, 64-bit Linux System calls)
• Zig

For instructions on how to run any specific implementation on Debian GNU/Linux 12 (Bookworm), see HOW_TO_RUN.md. All languages have been run in a Debian 12 Podman container with the instructions in that document.

I am experienced with some of those languages, and others I learned barely enough to implement this program as I was working on them.

Questions and Answers

Why?

Why not? It's what I find fun, and it's not the first time I've messed with ANSI escape sequences in the terminal.

It also gives me a sense of how different languages are designed.

The details

The output of the program should look like this:

The following is the pattern itself, with the ASCII escape character replaced by '␛':

␛[48;5;0m  ␛[48;5;1m  ␛[48;5;2m  ␛[48;5;3m  ␛[48;5;4m  ␛[48;5;5m  ␛[48;5;6m  ␛[48;5;7m  ␛[48;5;8m  ␛[48;5;9m  ␛[48;5;10m  ␛[48;5;11m  ␛[48;5;12m  ␛[48;5;13m  ␛[48;5;14m  ␛[48;5;15m  ␛[0m

␛[48;5;16m  ␛[48;5;17m  ␛[48;5;18m  ␛[48;5;19m  ␛[48;5;20m  ␛[48;5;21m  ␛[0m  ␛[48;5;52m  ␛[48;5;53m  ␛[48;5;54m  ␛[48;5;55m  ␛[48;5;56m  ␛[48;5;57m  ␛[0m  ␛[48;5;88m  ␛[48;5;89m  ␛[48;5;90m  ␛[48;5;91m  ␛[48;5;92m  ␛[48;5;93m  ␛[0m
␛[48;5;22m  ␛[48;5;23m  ␛[48;5;24m  ␛[48;5;25m  ␛[48;5;26m  ␛[48;5;27m  ␛[0m  ␛[48;5;58m  ␛[48;5;59m  ␛[48;5;60m  ␛[48;5;61m  ␛[48;5;62m  ␛[48;5;63m  ␛[0m  ␛[48;5;94m  ␛[48;5;95m  ␛[48;5;96m  ␛[48;5;97m  ␛[48;5;98m  ␛[48;5;99m  ␛[0m
␛[48;5;28m  ␛[48;5;29m  ␛[48;5;30m  ␛[48;5;31m  ␛[48;5;32m  ␛[48;5;33m  ␛[0m  ␛[48;5;64m  ␛[48;5;65m  ␛[48;5;66m  ␛[48;5;67m  ␛[48;5;68m  ␛[48;5;69m  ␛[0m  ␛[48;5;100m  ␛[48;5;101m  ␛[48;5;102m  ␛[48;5;103m  ␛[48;5;104m  ␛[48;5;105m  ␛[0m
␛[48;5;34m  ␛[48;5;35m  ␛[48;5;36m  ␛[48;5;37m  ␛[48;5;38m  ␛[48;5;39m  ␛[0m  ␛[48;5;70m  ␛[48;5;71m  ␛[48;5;72m  ␛[48;5;73m  ␛[48;5;74m  ␛[48;5;75m  ␛[0m  ␛[48;5;106m  ␛[48;5;107m  ␛[48;5;108m  ␛[48;5;109m  ␛[48;5;110m  ␛[48;5;111m  ␛[0m
␛[48;5;40m  ␛[48;5;41m  ␛[48;5;42m  ␛[48;5;43m  ␛[48;5;44m  ␛[48;5;45m  ␛[0m  ␛[48;5;76m  ␛[48;5;77m  ␛[48;5;78m  ␛[48;5;79m  ␛[48;5;80m  ␛[48;5;81m  ␛[0m  ␛[48;5;112m  ␛[48;5;113m  ␛[48;5;114m  ␛[48;5;115m  ␛[48;5;116m  ␛[48;5;117m  ␛[0m
␛[48;5;46m  ␛[48;5;47m  ␛[48;5;48m  ␛[48;5;49m  ␛[48;5;50m  ␛[48;5;51m  ␛[0m  ␛[48;5;82m  ␛[48;5;83m  ␛[48;5;84m  ␛[48;5;85m  ␛[48;5;86m  ␛[48;5;87m  ␛[0m  ␛[48;5;118m  ␛[48;5;119m  ␛[48;5;120m  ␛[48;5;121m  ␛[48;5;122m  ␛[48;5;123m  ␛[0m

␛[48;5;124m  ␛[48;5;125m  ␛[48;5;126m  ␛[48;5;127m  ␛[48;5;128m  ␛[48;5;129m  ␛[0m  ␛[48;5;160m  ␛[48;5;161m  ␛[48;5;162m  ␛[48;5;163m  ␛[48;5;164m  ␛[48;5;165m  ␛[0m  ␛[48;5;196m  ␛[48;5;197m  ␛[48;5;198m  ␛[48;5;199m  ␛[48;5;200m  ␛[48;5;201m  ␛[0m
␛[48;5;130m  ␛[48;5;131m  ␛[48;5;132m  ␛[48;5;133m  ␛[48;5;134m  ␛[48;5;135m  ␛[0m  ␛[48;5;166m  ␛[48;5;167m  ␛[48;5;168m  ␛[48;5;169m  ␛[48;5;170m  ␛[48;5;171m  ␛[0m  ␛[48;5;202m  ␛[48;5;203m  ␛[48;5;204m  ␛[48;5;205m  ␛[48;5;206m  ␛[48;5;207m  ␛[0m
␛[48;5;136m  ␛[48;5;137m  ␛[48;5;138m  ␛[48;5;139m  ␛[48;5;140m  ␛[48;5;141m  ␛[0m  ␛[48;5;172m  ␛[48;5;173m  ␛[48;5;174m  ␛[48;5;175m  ␛[48;5;176m  ␛[48;5;177m  ␛[0m  ␛[48;5;208m  ␛[48;5;209m  ␛[48;5;210m  ␛[48;5;211m  ␛[48;5;212m  ␛[48;5;213m  ␛[0m
␛[48;5;142m  ␛[48;5;143m  ␛[48;5;144m  ␛[48;5;145m  ␛[48;5;146m  ␛[48;5;147m  ␛[0m  ␛[48;5;178m  ␛[48;5;179m  ␛[48;5;180m  ␛[48;5;181m  ␛[48;5;182m  ␛[48;5;183m  ␛[0m  ␛[48;5;214m  ␛[48;5;215m  ␛[48;5;216m  ␛[48;5;217m  ␛[48;5;218m  ␛[48;5;219m  ␛[0m
␛[48;5;148m  ␛[48;5;149m  ␛[48;5;150m  ␛[48;5;151m  ␛[48;5;152m  ␛[48;5;153m  ␛[0m  ␛[48;5;184m  ␛[48;5;185m  ␛[48;5;186m  ␛[48;5;187m  ␛[48;5;188m  ␛[48;5;189m  ␛[0m  ␛[48;5;220m  ␛[48;5;221m  ␛[48;5;222m  ␛[48;5;223m  ␛[48;5;224m  ␛[48;5;225m  ␛[0m
␛[48;5;154m  ␛[48;5;155m  ␛[48;5;156m  ␛[48;5;157m  ␛[48;5;158m  ␛[48;5;159m  ␛[0m  ␛[48;5;190m  ␛[48;5;191m  ␛[48;5;192m  ␛[48;5;193m  ␛[48;5;194m  ␛[48;5;195m  ␛[0m  ␛[48;5;226m  ␛[48;5;227m  ␛[48;5;228m  ␛[48;5;229m  ␛[48;5;230m  ␛[48;5;231m  ␛[0m

␛[48;5;232m  ␛[48;5;233m  ␛[48;5;234m  ␛[48;5;235m  ␛[48;5;236m  ␛[48;5;237m  ␛[48;5;238m  ␛[48;5;239m  ␛[48;5;240m  ␛[48;5;241m  ␛[48;5;242m  ␛[48;5;243m  ␛[48;5;244m  ␛[48;5;245m  ␛[48;5;246m  ␛[48;5;247m  ␛[48;5;248m  ␛[48;5;249m  ␛[48;5;250m  ␛[48;5;251m  ␛[48;5;252m  ␛[48;5;253m  ␛[48;5;254m  ␛[48;5;255m  ␛[0m

The MD5 checksum of the output should be 5ee6c8ad78719bc2a515fbee5957ba06. Note: I am aware that it is trivial to find MD5 hash collisions, and would not rely on MD5 for security under any circumstance. Given the assumption that it looks right, and I just want to validate that nothing is off about the whitespace, I think it should be fine.

General program structure

Each implementation consists of 3 parts, each of which begins with a specific comment and follows the same general structure across implementations, though there is some flexibility depending on the specifics of the language.

Note that in the following pseudocode, print is assumed not to add a trailing newline, for loops work the way they do in C, and within strings, \e represents the ASCII escape character and \n represents the ASCII newline character.

Part 1 begins with something like the following comment:

Print the first 16 colors - these vary by terminal configuration

The general structure of part 1 can be expressed with the following pseudocode:

print("\n")
for (i=0; i < 16; i++) {
  print("\e[48;5;{i}m  ")
}
print("\e[0m\n\n")

Part 2 begins with something like the following comment:

Print the 6 sides of the color cube - these are more standardized, but the order is a bit odd, thus the need for this trickery

The general structure of part 2 can be expressed with the following pseudocode:

for (i=16; i < 52; i+=6) {
  for (ii=0; ii < 6; ii++) {
    print("\e[48;5;{i+ii}m  ")
  }
  print("\e[0m  ")
  for (ii=36; ii < 42; ii++) {
    print("\e[48;5;{i+ii}m  ")
  }
  print("\e[0m  ")
  for (ii=72; ii < 78; ii++) {
    print("\e[48;5;{i+ii}m  ")
  }
  print("\e[0m\n")
}
print("\n")
for (i=124; i < 160; i+=6) {
  for (ii=0; ii < 6; ii++) {
    print("\e[48;5;{i+ii}m  ")
  }
  print("\e[0m  ")
  for (ii=36; ii < 42; ii++) {
    print("\e[48;5;{i+ii}m  ")
  }
  print("\e[0m  ")
  for (ii=72; ii < 78; ii++) {
    print("\e[48;5;{i+ii}m  ")
  }
  print("\e[0m\n")
}
print("\n")

Part 3 begins with something like the following comment:

Finally, the 24 grays

The general structure of part 3 can be expressed with the following pseudocode:

for (i=232; i < 256; i++) {
  print("\e[48;5;{i}m  ")
}
print("\e[0m\n\n")

Common Implementation Variations

Due to the repetition of print("\e[48;5;{n}m ") for a value n, it may make sense to create a color_cell function for that, though as it's a one-line function, it may not be. Additionally, if it makes for cleaner or more idiomatic code in a given language, cube_row and/or cube_row_part functions may be defined for use in the second part. I first used that approach for some of the functional programming languages, but later used it more broadly, and have adjusted some of the implementations that predate my use of that approach to use it.

Depending on how simple and/or readable it is to represent an escape character within the source code, I might store it within an alias, macro, or global constant called ESC and use that.

An implementation that has such variations, using the same pseudocode "language" as before, would be as follows:

const ESC = "\e";

fn color_cell(n) {
  print(ESC + "[48;5;{n}m  ")
}

fn cube_row_part(n) {
  for (i=n; i < n+6; i++) {
    color_cell(i)
  }
}

fn cube_row(n) {
  cube_row_part(n)
  print(ESC + "0m    ")
  cube_row_part(n+36)
  print(ESC + "0m    ")
  cube_row_part(n+72)
  print(ESC + "0m  \n")
}

# Print the first 16 colors - these vary by terminal configuration
print("\n")
for (i=0; i < 16; i++) {
  color_cell(i)
}
print(ESC + "[0m\n\n")

# Print the 6 sides of the color cube - these are more standardized,
# but the order is a bit odd, thus the need for the above trickery
for (i=16; i < 52; i+=6) {
  cube_row(i)
}
print("\n")
for (i=124; i < 160; i+=6) {
  cube_row(i)
}
print("\n")

# Finally, the 24 grays
for (i=232; i < 256; i++) {
  color_cell(i)
}
print(ESC + "[0m\n\n")