README

fplox

Free Pascal (and Lazarus) implementation of clox bytecode virtual machine from the book Crafting Interpreters (http://craftinginterpreters.com))
Free Pascal and Lazarus: https://www.lazarus-ide.org

Added some of the optimizations:

• nan-boxing
• hash table optimization
• switch statement
• conditional expressions: print x == 5 ? "5" : nil;
• break and continue in loops
• interpolated strings, e.g. "this is $(2*21)."

also added:

• arrow functions, e.g.

fun add(a,b) -> a+b
fun sub(a,b) -> a-b
fun mul(a,b) -> a*b
fun div(a,b) -> a/b

print add(32,10);
print sub(52,10);
print mul(6,7);
print div(84,2);

• anonymous functions

// calculates the integral of a function over the interval a..b in n steps

fun integral(f, a, b, n) {
var sum = 0;
var dt = (b-a)/n;

for (var x = 0; x<n; x=x+1) {
sum = sum + f(a+(x+0.5)*dt);
}

return sum*dt;
}

// using arrow notation
print integral(fun(x)->xx-2x+4, 0, 1, 10000);
print integral(fun(x)->sqrt(1-x*x), -1, 1, 10000); // 1/2 PI

• declarations of local var in if-stmt e.g. if (var x=a; x<6) and while-stmt e.g.

while (var x=0; x<10) {
x=x-1;
print x;
}

• ensure statement to ensure a certain condition is true
• native functions e.g. print milliseconds();
  print pi();
  print sqrt(64);
  print sqr(8);
  print trunc(9.17);
  print frac(9.17);
  print date();
  print time();
  print now();
  print today();

randomize();
print random();
randLim(20);

print toNum("333");
print length("abcdef");
print toStr(99999);

error();