lang

lang is a simple stack based programming language
written in Python. It can either be interpreted in Python,
or be compiled to x86_64 assembly code using nasm. Note that
the compiled executables will only run on 64 bit linux distributions
since linux syscalls are used, although the Python simulation mode
should work on all modern operating systems.

Installation

  1. Clone repository
  2. Make sure you have nasm and ld in your path as these
    are used for compiling programs
  3. Install python dependcies:
    • pip install pathlib
  4. Try to run one of the example files:
    • Try to simulate: ./main.py examples/fib/fib.lang simulate and
    • Try to compile: ./main.py examples/dib/fib.lang compile examples/fib/fib.asm
    • Try to run the compiled file: ./examples/fib/fib
  5. Add the main.py to your system path somehow, e.g. save a bash script called lang in your ~/bin: 
    ~/coding/lang/main.py "$@"

    Then, you can do lang [program] [simulate | compile <out-file>]

Usage

Write a program with .lang extension, for example program.lang. Then you can either simulate
it in Python with lang program.lang simulate.
You can compile it to x86_64 assembly with lang program.lang compile program.asm. The compiled
assembly code will be stored in the file specified, in this case program.asm. Additionally, an
object file program.o will be generated, and the actual executable, simply named program with
no extension. To run it, run ./program.

Features

lang (name not final) is a very simple stack based language, and currently does not have features you might
be used to like variables, etc. Instead, you work with a stack.
A program consists of a series of instructions. Instructions are
separated by spaces, and newlines and excess whitespace are ignored.
You can use # to type comments, anything afer a # will be ignored.

Currently the only type of data that is supported is signed integers.
Nested if-else blocks and loops are supported.

Operation Syntax Description
PUSH int Push a number onto the stack, i.e. 45 pushes the number 45 onto the stack
POP pop Pop the top number off the stack
ADD + Pop the top two numbers off the stack, add them, and push the result back onto the stack
SUB - Pop the top two numbers a and b off the stack, subtract them (b - a), then push the result onto the stack
MUL * Pop the top two numbers a and b off the stack, multiply them, then push the result onto the stack
DIV / Pop the top two numbers a and b off the stack and performs integer division b // a on them. Then, pushes the ratio and remainder onto the stack, in that order, so the remainder is on top.
DUMP dump Pop the top number off the stack, and print it to standard output
DUP dup[n] dup will duplicate the top number on the stack and push it on top. dup2 will duplicate the second number from the top and push it to the top of the stack. You can also do dup3, etc.
SWAP swap Swaps the two topmost numbers on the stack
IF if Peeks at the top number off the stack. If it is 0, go to the next else or end. If it is nonzero, Go to the next instruction
EQ = Pops the top two numbers off the stack, and checks if they are equal. If they are, push 1 to the stack, otherwise push 0.
GE > Pops the top two numbers off the stack, and checks if the second number is greater than the top number. If it is, push 1 to the stack, otherwise push 0.
GEQ >= Pops the top two numbers off the stack, and checks if the second number is greater than or equal to the top number. If it is, push 1 to the stack, otherwise push 0.
LE < Pops the top two numbers off the stack, and checks if the second number is less than the top number. If it is, push 1 to the stack, otherwise push 0.
LEQ <= Pops the top two numbers off the stack, and checks if the second number is less than or equal to the top number. If it is, push 1 to the stack, otherwise push 0.
ELSE else If if fails, execution will jump to the else if one exists
END end Marks the end of an if-else block or a loop
WHILE while Peeks at the top number on the stack. If it is nonzero, execute the code until the next end. Then peek at the top number again and repeat until the top number is zero, then jump to the end

Examples

Code examples can be found in the examples directory, but here is an
example program that calculates the fibonacci numbers less than or equal to 1000
and prints them to standard output:

1 1 while
  dup dump
  swap dup2 +
  dup 1000 >= if 0 end
end

GitHub

View Github