Is this what you had in mind?

collect: aBlock until:quitBlock
	"Evaluate aBlock with each of the receiver's elements as the
argument. 
	Stop when quitBlock evaluates to true. 
	Collect the resulting values into a collection like the
receiver. Answer  
	the new collection."

	| newCollection |
	newCollection := self species new.
	self do: [:each |
		( quitBlock value:each )
			ifFalse:[
				newCollection add: (aBlock value: each)
			]
			ifTrue:[
				^newCollection.
			].
	].
	^ newCollection.


You might first look at #select:thenCollect: to see if it meets your
needs.  The "until" is a little stream-like, so you might also consider
moving items from a read stream to a write stream on a new collection
and then collect from it.

Bill




Wilhelm K. Schwab, Ph.D.
University of Florida
Department of Anesthesiology
PO Box 100254
Gainesville, FL 32610-0254

Email: bills at anest4.anest.ufl.edu
Tel: (352) 846-1285
FAX: (352) 392-7029