Source code in the smalltalk programming language

Object subclass: Hammer [
  Hammer class >> hammingNumbers: howMany [
    |h i j k x2 x3 x5| 
      h := OrderedCollection new.
      i := 0. j := 0. k := 0.
      h add: 1.
      x2 := 2. x3 := 2. x5 := 5.
      [ ( h size) < howMany ] whileTrue: [
        |m|
        m := { x2. x3. x5 } sort first.
        (( h indexOf: m ) = 0) ifTrue: [ h add: m ].
        ( x2 = (h last) ) ifTrue: [ i := i + 1. x2 := 2 * (h at: i) ].
        ( x3 = (h last) ) ifTrue: [ j := j + 1. x3 := 3 * (h at: j) ].
        ( x5 = (h last) ) ifTrue: [ k := k + 1. x5 := 5 * (h at: k) ]. 
      ].
      ^ h sort
  ]
].

(Hammer hammingNumbers: 20) displayNl.
(Hammer hammingNumbers: 1690) last displayNl.

limit := 10 raisedToInteger: 84.
tape := Set new.

hammingProcess := [:newHamming|
	(newHamming <= limit)
		ifTrue: 
			[| index |
			index := tape scanFor: newHamming.
			(tape array at: index) 
				ifNil: 
					[tape atNewIndex: index put: newHamming asSetElement.
					hammingProcess value: newHamming * 2.
					hammingProcess value: newHamming * 3.
					hammingProcess value: newHamming * 5]]].

hammingProcess value: 1.

sc := tape asSortedCollection.
sc first: 20. "a SortedCollection(1 2 3 4 5 6 8 9 10 12 15 16 18 20 24 25 27 30 32 36)"
sc at: 1691. "2125764000" 
sc at: 1000000. "519312780448388736089589843750000000000000000000000000000000000000000000000000000000"

tape := Heap with: 1 -> 1.
hammingStream :=
	[| next |
	next := tape removeFirst.
	next value <= 2 ifTrue: [tape add: next key * 2 -> 2].
	next value <= 3 ifTrue: [tape add: next key * 3 -> 3].
	next value <= 5 ifTrue: [tape add: next key * 5 -> 5].
	next key]
		reading.

hammingStream read: 20. "get first 20 values => #(1 2 3 4 5 6 8 9 10 12 15 16 18 20 24 25 27 30 32 36)"
hammingStream ++ 1670. "skip the next 1670 values"
hammingStream get. "and the 1691th value is => 2125764000".
hammingStream ++ (999999 - 1691). "now skip more to position at 999,999".
hammingStream get. "and the 1,000,000th value is =>  519312780448388736089589843750000000000000000000000000000000000000000000000000000000".
tape size. "See how many we have buffered =>  24904"