Controlling robots in remotely-operated laboratory using Objection language

Our goal is to enable robots in virtual laboratory to be controlled using the Objection programming language.

Challenges

• The Objection language runtime is written in Delphi and has not been ported to platforms other than Win32 yet
• The codebase of Objection language needs to be reorganized in a way that will allow extending it with Robot library bindings, yet ensure that the runtime core remains independent of it.
• It should be possible to replace the runtime core with a newer Objection version with as little effort as possible
• Integration to existing virtual laboratory system
• End user interface

Language

Objection is a multiparadigm programming language, written partially in itself. Every value is a first class object, including functions. Blocks of code are anonymous functions and language constructs such as loops only manipulate with functions. All of this is hidden underneath a classical, structured syntax, but remains fully accessible for the user to explore.

Here is a short list of Objection features:

• garbage collection
• optimized tail recursion
• first class functions
• anonymous functions
• closures
• generators (via the yield keyword)
• duck typing
• all values are objects
• prototype object model (can be used indirectly using class-like syntactic sugar)
• operator overloading
• basic data structures literals
• infinite lists (via generators)
• classes and metaclasses
• objects ex nihilo
• natural language constructs
• powerfull built-in higher order operators
• eager evaluation
• support for return, break and continue commands
• compiled to bytecode interpreted by Objection Virtual Machine
• editor supporting syntax highlighting (Windows only)

Here is a short list of features that Objection currently lacks:

• short circuit evaluation of boolean operators
• call-by-reference for function arguments
• exceptions
• properties
• large numbers
• sane class library
• API for calling external libraries
• speed

Very basic language examples

Some prime numbers

 var primes := {} 
 for n in 2..100 do 
 [ 
     var isPrime := yes 
     for p in primes do 
         if n mod p = 0 then 
         [
             isPrime := no 
             break 
         ]    	 
     if isPrime then 
     primes.Add(n) 
 ]
 
 print primes

 # The same, still slow, but a bit compressed
 var primes := {} 
 for n in 2..100 do 
     if not ([p | n mod p = 0] in primes) then 
         primes.Add(n) 
    print primes

Quicksort

 # This code can be written way shorter, and way less readable
 function Sort |list|
     if list.Length() = 0 then
         return {}
 
     var pivot := list.Head()
     var lesser := Sort(list.Tail() where [x|x<=pivot])
     var greater := Sort(list.Tail() where [x|x>pivot])
 
     lesser ++ {pivot} ++ greater

Computing factorial using Y combinator

 # Actually using applicative-order version of Y combinator for "recursion"
 var Z := [f| [x|f([y|x(x)(y))]([x|f([y|x(x)(y))]) ]

 var Fact := [f| [x|if x = 0 then [1] else [x*f(x-1)]]]
 print Z(Fact)(6)

Infinite lazy lists

 function Naturals
     var i := 0
     while yes
         yield i
         i ++ 1
 
 for i in Naturals.Take(50) do
     print i       # prints numbers 0 .. 50
 
 var squares := Naturals change [x|x^2]
 # "squares" now contains ordered squares of all natural numbers
 
 var squaresGreaterThanMillion = squares where [x|x>1000000]
 
 print squaresGreaterThanMillion.Take(1)  
 # Prints first square of a natural number greater than million

More examples and tutorial

More examples and a somehow lacking and incomplete language tutorial can be found at [[1]]. The site also contains a full listing of Objection standard library (written in Objection), from which a lot of more advanced language features can be deduced. A minimalistic language IDE and a runtime can be obtained at [[2]] for experimentation. All information provided there is unfortunately in Slovak language only.

Project implementation notes

The Robot library bindings are accessible as a class methods of class Robot of Objection runtime.