Asciicast.jl is all about showcasing Julia code running in a REPL using technologies developed by the open-source asciinema project. (It is totally unaffiliated with the authors of that project, however).

It does so in a few ways:

  • provides a convenient way to generate and maintain gifs showing code execution in READMEs and other documents. See the Markdown Usage portion of the docs.
  • provides integration with Documenter, providing @cast Documenter blocks that render code outputs as gifs in Documenter websites. See the Documenter Usage portion of the docs.
  • provides functionality to generate asciicast files (using the v2 file format) from Julia code, using the cast"" string macro, a record_output function, or using low-level write_event commands. These files can be played in the terminal or uploaded to with the asciinema player, or played in a web browser using asciinema-player. See the docs for more.


@info "Hello!"
println("That was a logging statement, but this is printing.")
x = rand(10, 10)
using LinearAlgebra
println("Now I'll wait a second")
println("ok, done!")

Alternatives to Asciicast.jl

  • It is easy to use the CLI tool asciinema directly to record sessions to .cast files or otherwise. That can be a good option if you need keyboard input or face some of the other Limitations of asciicast.jl.
    • In contrast, Asciicast.jl has an advantage in maintainability, in that you don't need to manually re-run sessions to regenerate the outputs.
  • Replay.jl provides a similar Julia-based alternative. Some of the differences I can ascertain:
    • Asciicast.jl is based on Documenter's code execution sandboxes (which have their limitations), while Replay.jl has it's own implementation.
    • Asciicast.jl provides Documenter and pandoc-based document integration with @cast blocks and {cast="true"} blocks, while Replay seems focused on the core replaying-of-sessions. Perhaps these could be composed together somehow?
    • Possibly other differences; I am not very familiar with Replay.jl. PRs to improve this comparison are appreciated!