My own Smalltalk has these:

Enumerable
�� methods for: 'enumerating'
�� limit: n do: aBlock
�� "Pass elements of the receiver to aBlock one at a time,
�� as for #do:, but stop after n elements.�� n must be a
�� non-negative SmallInteger.�� Which elements you get is
�� for the receiver to decide."
�� |count|
�� n < 1 ifTrue: [
�� n = 0 ifTrue: [^self]ifFalse: [self pvtCountError: n]].
�� count := 0.
�� self do: [:each |
�� aBlock value: each.
�� (count := count + 1) < n ifFalse: [^self]].
AbstractKeyedCollection
�� methods for: 'enumerating'
�� limit: n keysAndValuesDo: aBlock��
�� "Pass keys and corresponding values of the receiver
�� to aBlock one at a time, as for #keysAndValuesDo:,
�� but stop after n elements.�� See #limit:do:."
�� |count|
�� n < 1 ifTrue: [
�� n = 0 ifTrue: [^self]ifFalse: [self pvtCountError: n]].
�� count := 0.
�� self keysAndValuesDo: [:key :value |
�� aBlock value: key value: value.
�� (count := count + 1) < n ifFalse: [^self]].

Enumerable is the superclass of Collection; it doesn't cover streams but does

cover 2- and 3-dimensional arrays.�� AbstractKeyedCollection covers both

dictionaries and sequences. Since they only depend on #do: and #keysAndValuesDo:

respectively, they should fit nicely into some sort of Trait(s).

I gave a great deal of thought to the names, and decided on "limit" since it

is already in use in a similar sense in things like LimitedOutputStream or

#printStringLimitedTo:.�� I did consider #do:limitedTo: and #keysAndValuesDo:limitedTo:

which would be more consistent with #streamContents:limitedTo:, but "heavy" things

like blocks really work better at the end.