September Morn Update

Task/Extensible-prime-generator/Python/extensible-prime-generator-4.py

@@ -0,0 +1,25 @@
+from itertools import count, takewhile, islice
+
+def prime_sieve():
+    sieved = count(2)
+    prime = next(sieved)
+    yield prime
+    primes = [prime]
+    for x in sieved:
+        if any(x % prime == 0 for prime in primes):
+            continue
+        yield x
+        primes.append(x)
+
+if __name__ == '__main__':
+    def leq_150(x): return x <= 150
+    def leq_8000(x): return x <= 8000
+
+    print("Show the first twenty primes.\n   =",
+        list(islice(prime_sieve(), 20)))
+    print("Show the primes between 100 and 150\n   =",
+        [x for x in takewhile(leq_150, prime_sieve()) if x >= 100])
+    print("Show the number of primes between 7,700 and 8,000.\n   =",
+        sum(1 for x in takewhile(leq_8000, prime_sieve()) if x >= 7700))
+    print("Show the 10,000th prime.\n   =",
+        next(islice(prime_sieve(), 10000-1, 10000)))