Languages as means of writing programs

Literate programming tools have to strike a balance about how much they want to know about the programming language being used in a web. If they get too close, the result can be a tool wedded to a single language, just as the original WEB really cannot be used with anything other than a long-dead dialect of Pascal. But if they take a principled stand that they know nothing about the language, then they end up feature-poor, and produce weaves which are a little bland.

Inweb aims to allow quite a wide variety of programming languages, but needs the user to brief it on any language it does not already know. Running:

$ inweb inspect -resources

lists all Inweb's built-in resources, and at time of writing only 24 of them are languages: since quite a few are obscure (for reasons to do with the needs of the Inform project, which Inweb spun out of), an Inweb user is quite likely to need to add new languages sooner or later.

Fortunately, language declarations can be surprisingly short and easy, so this is not a huge task.

Languages as ways to syntax-colour text

The author of a large web may want to display snippets of console output, pseudocode, pieces of programs in other languages, examples of usage, and so on. These aren't part of the web's program as such, and all vanish away in a tangle. But in the woven form of the web, they need to look right.

But how is Inweb to do that? Inweb uses a combination of syntax-colouring and (in HTML output) CSS styling to make a chunk of C look different from a chunk of console output, for example. But in order to do that, in needs to be told what each chunk is. For example (in MarkdownCode notation):

This is a basic tangling command:

``` ConsoleText
$ inweb tangle countsort.py.md
tangling web "Counting Sort" (Python program in MarkdownCode notation) to file 'countsort.py'
```

Here the displayed material, inside a Markdown "fence" provided by the backticks, is declared as being ConsoleText.

This is in fact a "language", as far as Inweb is concerned. (It's one of the ones supplied with Inweb.) Inweb doesn't distinguish between languages you might want to program in, and schemes for colouring up text being displayed in a weave. As a pretty extreme example:

Language "VowelsExample" {
	colour !vowel like !function
	colouring
		=> !plain
		characters in "AEIOUaeiou" {
			=> !vowel
		}
	end
}

This language is evidently just a colouring scheme (it takes plain text and highlights the English vowels in it), not something to write programs in.

All of this is to say that an Inweb language is a combination of a few notes about its syntax or quirks, together with instructions on how to syntax-colour its code, but both parts are optional.