esolang/velato repository overview

⁠Velato programming language

• Official Referrence of Velato⁠

This image is a part of esolang-box 2.3.0⁠.

⁠About

esolang-box project⁠ aims to provide easy and normalized interface for many (currently 229 (!)) programming languages by Docker, especially to uncommon esoteric programming languages⁠.

The implementation and interpreter of language Velato is included in this image and can be invoked by the simple one command velato. (it's also an alias of script command, so you can use either.)

This script accepts standard input as the input of program and the first argument as program code file. The output of the script will be printed into standard output. This convension is shared between all esolang-box images⁠, so you can use another language easily.

⁠Usage example

⁠Run a single Velato script

Supposing you have hello world script hello.velato.mid in the current directory like this:

$ ls
hello.velato.mid

You can execute it with the following command:

$ docker run --rm -v "$PWD":/code:ro esolang/velato velato /code/hello.velato.mid
Hello, World!

⁠Processing input

$ docker run -i --rm -v "$PWD":/code:ro esolang/velato velato /code/hello.velato.mid < input.txt

⁠Debug code with shell

$ docker run -it --rm -v "$PWD":/code:ro esolang/velato sh
# velato /code/hello.velato.mid
Hello, World!

⁠Observing usage of exec syscalls

esolang-box 2.3.0 supports tracing of execve and execveat syscalls by strace command. Setting STRACE_OUTPUT_PATH environment variables and enabling ptrace will produce strace log to the specified path.

$ docker run --cap-add=SYS_PTRACE --rm -v "$PWD":/code --env STRACE_OUTPUT_PATH=/code/strace.txt esolang/velato velato /code/hello.velato.mid
Hello, World!

Some considerations:

• Enabling ptrace breaks seccomp filter before kernel 4.8.⁠ You should be very careful to use --cap-add=SYS_PTRACE (especially you must not use it with Xenial).
• Using strace costs a huge performance overhead and syscalls may be 10x slower.