Fibonacci numbers example

from __future__ import annotations

from egglog import *

egraph = EGraph()


@egraph.function
def fib(x: i64Like) -> i64:  # type: ignore[empty-body]
    ...


f0, f1, x = vars_("f0 f1 x", i64)
egraph.register(
    set_(fib(0)).to(i64(1)),
    set_(fib(1)).to(i64(1)),
    rule(
        eq(f0).to(fib(x)),
        eq(f1).to(fib(x + 1)),
    ).then(set_(fib(x + 2)).to(f0 + f1)),
)
egraph.run(7)
egraph.check(eq(fib(i64(7))).to(i64(21)))
egraph