ch21 examples

21-futures/primes/primes.py

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+#!/usr/bin/env python3
+
+import math
+
+
+PRIME_FIXTURE = [
+    (2, True),
+    (142702110479723, True),
+    (299593572317531, True),
+    (3333333333333301, True),
+    (3333333333333333, False),
+    (3333335652092209, False),
+    (4444444444444423, True),
+    (4444444444444444, False),
+    (4444444488888889, False),
+    (5555553133149889, False),
+    (5555555555555503, True),
+    (5555555555555555, False),
+    (6666666666666666, False),
+    (6666666666666719, True),
+    (6666667141414921, False),
+    (7777777536340681, False),
+    (7777777777777753, True),
+    (7777777777777777, False),
+    (9999999999999917, True),
+    (9999999999999999, False),
+]
+
+NUMBERS = [n for n, _ in PRIME_FIXTURE]
+
+# tag::IS_PRIME[]
+def is_prime(n: int) -> bool:
+    if n < 2:
+        return False
+    if n == 2:
+        return True
+    if n % 2 == 0:
+        return False
+
+    root = math.isqrt(n)
+    for i in range(3, root + 1, 2):
+        if n % i == 0:
+            return False
+    return True
+# end::IS_PRIME[]
+
+if __name__ == '__main__':
+
+    for n, prime in PRIME_FIXTURE:
+        prime_res = is_prime(n)
+        assert prime_res == prime
+        print(n, prime)