Liquidy

This is a sample demonstrating creating a Ruby module written in Rust which then evaluates Ruby code from inside Rust.

Setup

You'll need a Ruby installed on your machine and configured in your path, for example with chruby:

chruby 2.6.5

At this point you should be able to build the gem:

rake

Testing it out

There's a script in bin/console that will set up a REPL with the gem loaded:

$ bin/console
irb(main):001:0>

At this point you can evaluate some Ruby code through the Rust module:

irb(main):004:0> LiquidyVM.evaluate "puts 'Hello world'"
Rust: evaluating "puts \'Hello world\'"
Hello world
Rust: result is Ok(AnyObject { value: Value { value: 8 } })
Rust:    ... as string: Err(#<TypeError: Error converting to String>)
Rust:    ... as number: Err(#<TypeError: Error converting to Fixnum>)
=> nil

You'll see that it prints out "Hello world" as expected. It also tries to convert the expression to a string and a number. In this case, puts returns nil so both those fail. If you give it an expression then it will print the result there showing that the Rust code can convert the string or numeric values to Rust values:

irb(main):001:0> LiquidyVM.evaluate "'hello' + ' ' + 'world'"
Rust: evaluating "\'hello\' + \' \' + \'world\'"
Rust: result is Ok(AnyObject { value: Value { value: 140710980816280 } })
Rust:    ... as string: Ok("hello world")
Rust:    ... as number: Err(#<TypeError: Error converting to Fixnum>)
=> "hello world"
irb(main):006:0> LiquidyVM.evaluate "55 + 42"
Rust: evaluating "55 + 42"
Rust: result is Ok(AnyObject { value: Value { value: 195 } })
Rust:    ... as string: Err(#<TypeError: Error converting to String>)
Rust:    ... as number: Ok(97)
=> 97

Organization

• bin: Shell scripts for running the project. The important one is bin/console which starts an IRB shell with the gem loaded.
• lib: The Ruby code that loads the module.
• src: The Rust implementation of the module. It defines a LiquidityVM class with an evaluate method that basically works like eval.