September Morn Update

Task/Extensible-prime-generator/Nim/extensible-prime-generator-1.nim

@@ -0,0 +1,60 @@
+import tables
+
+type PrimeType = int
+
+proc primesHashTable(): iterator(): PrimeType {.closure.} =
+  iterator output(): PrimeType {.closure.} =
+    # some initial values to avoid race and reduce initializations...
+    yield 2.PrimeType; yield 3.PrimeType; yield 5.PrimeType; yield 7.PrimeType
+    var h = initTable[PrimeType,PrimeType]()
+    var n = 9.PrimeType
+    let bps = primesHashTable()
+    var bp = bps() # advance past 2
+    bp = bps(); var q = bp * bp # to initialize with 3
+    while true:
+      if n >= q:
+        let inc = bp + bp
+        h.add(n + inc, inc)
+        bp = bps(); q = bp * bp
+      elif h.hasKey(n):
+        var inc: PrimeType
+        discard h.take(n, inc)
+        var nxt = n + inc
+        while h.hasKey(nxt): nxt += inc # ensure no duplicates
+        h.add(nxt, inc)
+      else: yield n
+      n += 2.PrimeType
+  output
+
+var num = 0
+stdout.write "The first 20 primes are:  "
+var iter = primesHashTable()
+for p in iter():
+  if num >= 20: break else: stdout.write(p, " "); num += 1
+echo ""
+stdout.write "The primes between 100 and 150 are:  "
+iter = primesHashTable()
+for p in iter():
+  if p >= 150: break
+  if p >= 100: stdout.write(p, " ")
+echo ""
+num = 0
+iter = primesHashTable()
+for p in iter():
+  if p > 8000: break
+  if p >= 7700: num += 1
+echo "The number of primes between 7700 and 8000 is:  ", num
+num = 1
+iter = primesHashTable()
+for p in iter():
+  if num >= 10000:
+    echo "The 10,000th prime is:  ", p
+    break
+  num += 1
+var sum = 0
+iter = primesHashTable()
+for p in iter():
+  if p >= 2_000_000:
+    echo "The sum of the primes to two million is:  ", sum
+    break
+  sum += p

Task/Extensible-prime-generator/Nim/extensible-prime-generator-2.nim

@@ -0,0 +1 @@
+for p in primesPaged():

Task/Extensible-prime-generator/Nim/extensible-prime-generator-3.nim

@@ -0,0 +1 @@
+for p in iter():