What is your implementation with with:collection: ? I know this function from python, they call it "zip" we could implement this in SequenceableCollection SequenceableCollection>>zip: aCollection | index | index := 0. self size > aCollection size ifTrue:[ ^ aCollection zip: self]. ^ self class new: (aCollection size + self size) streamContents: [:stream | aCollection do: [:each | index:=index + 1. stream nextPut: each ] separatedBy: [(index > self size) ifFalse:[stream nextPut: (self at:index) ]]] Another example, using a generator (I didn't used Generator before, but I like the idea to create an endless stream from a string, with some fill value (empty string in this case)). |gen| gen := Generator on:[:g | '123' do:[:k | g yield: k asString ] . [true] whileTrue:[g yield:'']]. String streamContents:[:stream | 'abcdefg' do:[:c | stream nextPut: c] separatedBy:[ stream nextPutAll:gen next]] 2016-03-15 2:09 GMT+01:00 Andy Burnett <andy.burnett@knowinnovation.com>:

I have two strings, which are typically of different lengths, and I want to interleave them, i.e.:

'abcdefg' interleaveWith: '123'

Would produce

'a1b2c3defg'

I know how to write this procedurally, but I have been very impressed by what Sven shows in his Medium articles, so I wondered if there is any existing mechanism that would allow me to solve this elegantly? with:collection: almost does it, but the collections have to be the same size.

Cheers Andy