But this already exist, at least for SequenceableCollection, try:

(1 to: 4) combinations: 2 atATimeDo: [:e | Transcript cr; show: e
printString]

2016-02-26 16:05 GMT+01:00 <commits at source.squeak.org>:

> A new version of Collections was added to project The Inbox:
> http://source.squeak.org/inbox/Collections-pre.679.mcz
>
> ==================== Summary ====================
>
> Name: Collections-pre.679
> Author: pre
> Time: 26 February 2016, 4:04:56.205127 pm
> UUID: 2ac5821c-d6f5-418c-ab07-ed3c2b9de62c
> Ancestors: Collections-eem.678
>
> This is a new iteration method which allows the iteration over asymmetric
> pairs. I have found this useful in game collision detections or duplicate
> detections. Alternatively we might want to take a second collection as
> input and create asymmetric pairs from self and this second collection.
>
> =============== Diff against Collections-eem.678 ===============
>
> Item was added:
> + ----- Method: Collection>>asymmetricPairsDo: (in category 'accessing')
> -----
> + asymmetricPairsDo: aBlock
> +
> +       | iterationCollection currentElement |
> +       iterationCollection := self copy.
> +
> +       [currentElement := iterationCollection anyOne.
> +       iterationCollection remove: currentElement.
> +       iterationCollection isEmpty not]
> +               whileTrue: [ iterationCollection
> +                       do: [:element | aBlock value: currentElement
> value: element]].!
>
>
>
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