PARSER

a = 10
b = 20
c = 30

my_array = [1,2,3]

push my_array, 20
a = pop my_array



-- this is a comment
-- yadda yadda yadda
def calculate(a, b = 20, c = 30) {
  local x, y, z
  
  length(my_array)
  
  while a < b {
    a = a + c
  }
  
  if c % 2 == 1 {
    
  } else if c % 3 == 1 {
    
  } else {
  
  }
  
  -- for, foreach
  
  
  
  foreach my_array => i {
    print i
  }

}

def draw(a, b, c) {
  pen #ff0000  -- function calls
  linewidth 5
  moveto 10, 10
  lineto 30, 30
  lineto 50, 100
}

def blue(isOn) {
  fill isOn ? #blue : #black
  pen #white
  circle 100, 100, 50
}

def red(isOn) {
  fill isOn ? #red : #black
  pen #white
  circle 300, 100, 50
}

def run {
  while true {
    red on
    blue off
    wait 0.5
    red off
    blue on
    wait 0.5
  }
}

how does scoping work?
 - in the root scope, variables can be declared without `local`
 - variables declared in root scope never escape the compilation unit
 - variables are lexically scoped
 - block scoping for locals
 
open questions:
 - computed properties e.g. canvas width/height
 - constants
 
ternary operator
  - modify to support stashing of last computed result
  - in empty 'if' blocks, set last result to null/undefined
  - ternary operator then becomes if/else compilation + push last computed value