Language

An implementation of a C-style statically typed language that compiles down to a bytecode which is then interpreted.

Progress

• Lex basic scripts
• Parse arithmetic expressions
• Lex and parse comparison expressions
• Lex and parse variables
• Parse statments
• Type check statements and expressions
• Compile things so far
• Compile and run if-else statements
• Compile and run functions
• Compile and run native functions
• Compile and run while loops
• Use Main function as entry point to program
• Implement arrays
• Implement strings
• Implement multidimensional arrays
• Implement structs
• Implement struct inheritance
• Interfacing with C/C++ libraries
• Serialise and de-serialise Functions in order to seperate compilation and execution
• Optimiser
  • Evaluate constant expressions at compile time
  • Propagate constants through program
  • Keep performing optimisation passes until the AST does not change
  • Control flow optimisations
  • Peephole optimisations of bytecode
• Multiple file programs
• Verification
  • Lex and parse verification statements
  • Push precondition through bytecode for a subset of the language
  • Verify output

Long-term Goals

• Improve garbage collector heuristics to minimise loss of program execution time

Known bugs TODO

• Overloading of functions where the overloaded types are assignable to each other
  • MBE:

    function void Foo(int i){...}
    function void Foo(double d){...}
    
    Foo(3.14); // would have called the int version
               // not the double version as it appears
               // first and ints can be assigned to doubles 

• Put parsed library functions into different container than normal functions
• Implicit type conversions for elements of braced initialisers are not implemented
  • MBE:

    Array<int> arr = {3.141, 1.618, 1.414};
    // compiled as:
    // LOAD_DOUBLE 0 (value 3.141) should be --> LOAD_INT 0 (value 3)
    // LOAD_DOUBLE 1 (value 1.618) should be --> LOAD_INT 1 (value 1)
    // LOAD_DOUBLE 2 (value 1.414) should be --> LOAD_INT 2 (value 1)
    // etc.

Example Programs

Hello World!

function void Main()
{
    Print("Hello World!");
}

A simple program to calculate the Fibbonacci numbers

function int Fib(int n)
{
    if (n < 1)
        return n;
 
    return Fib(n - 1) + Fib(n - 2);
}

function void Main()
{
    Print(Fib(10));
}

Verification

Example 1

function int Square(int x)
(|x = x_0|)
{
    return x * x;
    (|x_0 * x_0|)
}