The Wig programming language

This is a description of the Wig programming language.

As yet, Wig is not much more than a gleam in the author’s eye, so expect this guide to be inconsistent, incomplete, and unusable.

Some goals for Wig:

  • This is a personal project. Progress will be slow. Features may be included or excluded at the author’s whim.

  • Experiment with some ideas. Many of these may seem weird at first sight, but the point is to discover how well they work in practice.

  • Wig will be an imperative language, with a declarative subset. How large that subset is remains to be seen.

  • The concepts used by Wig will be built from a few very primitive notions. Even to the extent that we will use Wig to describe, for example, what integers are and how they behave.

  • The initial version will be an interpreter written in Go.

  • Eventually, the author hopes to replace that with a compiler written in Wig itself.

Getting started

To build Wig, you will need a Go compiler.

The source code for Wig is available at https://github.com/pat42smith/wig.

TODO

Actually, it’s not there yet.

After you have downloaded a copy of the source code, you can build Wig by going to the top level directory and running the command go build. This should create an executable file named wig (or wig.exe on Windows) in the current directory. You might want to copy this file to one of the directories in your search path.

To run a simple program, copy this text into a file, say hello.wig:

proc main()
   'Println("Hello, world!")

Now run the program with the command wig hello.wig. You should see this output:

Hello, world!

A few notes on this program:

  • Each program should contain a procedure named main, which will be executed when the program is run.

  • The single quote ' is used for scoping. When used by itself before a name, it indicates the name should be looked up in the standard library.

  • 'Println is a standard library function that prints its arguments separated by spaces and followed by a newline character.

  • Wig uses indentation to mark program structure, so the body of main is indented.

TODO

Link to more information about scoping with single quotes. Link to more information about blocks. Link to more information about the standard library and Println.

Examples

This document contains many small example programs. These are copied from the Wig test suite. The program above is part of one such example; the full example reads:

proc main()
   'Println("Hello, world!")

#>Hello, world!

Wig ignores the last line, because # starts a comment.

TODO

Link to a fuller description of comments.

However, the test framework recognizes a line beginning with #>, and treats the rest of the line as output that should appear when the example program is run. A line beginning with #! describes expected error output:

proc main()
   nonesuch("Hello, world!")

#!examples/nonesuch.wig:2:4: nonesuch undefined

You can run the full test suite by going to the top directory of the wig source tree and running one of the commands ./runtests or go test. In either case, you must first install the invigilate program from https://github.com/pat42smith/invigilate.

TODO

Make these work.

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