test.py

from nmigen import *
from nmigen.cli import main

class Test:
    def __init__(self):
        self.out = Signal(8)

    def get_fragment(self, platform):
        data = list(range(10))
        arr = Array(data)
        idx = Signal(max=len(data))

        m = Module()
        m.d.comb += self.out.eq(arr[idx])
        m.d.sync += idx.eq(idx + 1)
        return m.lower(platform)

test = Test()
main(test, ports=[test.out])