70 lines
3.9 KiB
Markdown
70 lines
3.9 KiB
Markdown
## Criteria for language inclusion
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I aspire for Riju to support more languages than any reasonable person
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could conceivably think is reasonable. That said, there are some
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requirements:
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* **Language must have a clear notion of execution.** This is because
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a core part of Riju is the ability to execute code. Languages like
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[YAML](https://yaml.org/), [SCSS](https://sass-lang.com/), and
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Markdown are fine because they have a canonical transformation (into
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[JSON](https://www.json.org/json-en.html),
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[CSS](https://developer.mozilla.org/en-US/docs/Web/CSS), and
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[HTML](https://developer.mozilla.org/en-US/docs/Web/HTML)
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respectively) that can be performed on execution. However, languages
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like JSON, CSS, and HTML are not acceptable, because there's nothing
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reasonable to do when they are run.
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* **Language must not require input or configuration.** This is
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because, in order to avoid bloating the interface, Riju provides a
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way to supply code but not any other data. Of course, it's possible
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to supply input interactively, so reading stdin is allowed, but if a
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language can only reasonably be programmed with additional input,
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it's not a candidate for inclusion. Thus, many templating languages
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are excluded, since they don't do anything unless you are
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substituting a value. However, some languages such as
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[Pug](https://pugjs.org/) are allowed, because they implement a
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significant syntax transformation outside of template substitution.
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Also, languages like [Sed](https://www.gnu.org/software/sed/) and
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[Awk](https://www.gnu.org/software/gawk/) are allowed, because it's
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straightforward to test code written in them even without a
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pre-prepared input file.
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* **Language must not require a graphical environment.** This is
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because we use a pty to run code, and there is no X forwarding. As
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such, we can't use languages like
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[Scratch](https://scratch.mit.edu/),
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[Alice](https://www.alice.org/), and
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[Linotte](http://langagelinotte.free.fr/wordpress/).
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* **Language must be available for free under a permissive license.**
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This is because we must download and install all languages
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noninteractively in the Docker image build, so anything that
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requires license registration is unlikely to work (or be legal). We
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can't use [Mathematica](https://www.wolfram.com/mathematica/) or
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[MATLAB](https://www.mathworks.com/products/matlab.html), for
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example, but we can use [Mathics](https://mathics.github.io/) and
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[Octave](https://www.gnu.org/software/octave/), which provide
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compatible open-source implementations of the underlying languages.
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* **Language must be runnable under Docker on Linux.** This is because
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that's the execution environment we have access to.
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[AppleScript](https://en.wikipedia.org/wiki/AppleScript) is out
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because it only runs on macOS, and [Docker](https://www.docker.com/)
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is out because it can't be run inside Docker (without the
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`--privileged` flag, which has unacceptable security drawbacks; see
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[#29](https://github.com/raxod502/riju/issues/29)). Note, however,
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that many Windows-based languages can be used successfully via
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[Mono](https://www.mono-project.com/) or
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[Wine](https://www.winehq.org/), such as
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[Cmd](https://en.wikipedia.org/wiki/Cmd.exe),
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[C#](https://en.wikipedia.org/wiki/C_Sharp_(programming_language)),
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and [Visual Basic](https://en.wikipedia.org/wiki/Visual_Basic).
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Here are some explicit *non-requirements*:
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* *Language must be well-known.* Nope, I'll be happy to add your pet
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project; after all, [Kalyn](https://github.com/raxod502/kalyn) and
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[Ink](https://github.com/thesephist/ink) are already supported.
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* *Language must be useful.* I have no objection to adding everything
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on the esolangs wiki, if there are interpreters/compilers available.
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* *Language must be easy to install and run.* Well, it would be nice,
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but I've seen some s\*\*\* when adding languages to Riju so it will
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take a lot to surprise me at this point.
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