programming language wrapper for iOS devices
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Scribble is desgined to be a family of languages designed such that you can scribble them on an iPhone, iPad or iPod touch device without having to switch into the modal character insertion panel - i.e. you can write more of the language using just the characters on the main keyboard of the iOS device.

Scribble syntaxes need to meet these criteria:

  1. Easy to write on an iOS touchscreen device without a physical keyboard.
  2. Syntax must be derived based on real-life experience of using REPL over SSH on iOS devices.
  3. Be as simple as possible and adhere to the rule of least surprise in both syntax and implementation.
  4. Provide a REPL.
  5. Compile down to an existing language.
  6. Be easy to run on a wide variety of platforms - it should be relatively simple to implement on, say, the JVM or CLR.

The use case for Scribble languages is simple: to use as a calculator, to simply try out an algorithm and for other rapid prototyping needs on a handheld device.

This implementation: Ruby

This particular implementation of Scribble runs on top of Ruby on the Java Virtual Machine. It uses the JRuby JSR 223 implementation to wrap around a REPL.

It is currently very primitive but offers the following syntactical changes from Ruby:

  • gt, lt, gte, lte, eq - these are substituted for operators
  • add and times in place of + and *
  • variable allocation using !
  • one-place lambda creation using ,,

What does the code look like then?

[1,2,3,4,5].map ,, x plus x

is equivalent to

[1,2,3,4,5].map do |x| x + x end

But requires a lot fewer keystrokes on iOS devices. Assigning variables is done like this:

a ! 5

And comparison is done using the plain text operators:

5 gt 1

This will be documented and developed further, but in the spirit of Why Day I wanted to put it out there quickly.

Implementation status

Target language: Ruby

Implementation platform: JVM via JRuby

  • Syntax designed - check!
  • Simple regex parser written - check!
  • Simple REPL implemented - check!
  • Compiler implemented
  • Extract as much functionality into separate Ruby module
  • Packaged as binary

Ready for normal people to use? Well, it won't ever be. Normal people don't fire up REPLs over SSH connections on their iPads. Ready for geek use? Not quite yet.