Hi everyone,

I'm a Pharo newbie with some knowledge about Smalltalk. Surfing through the code base I stumbled over the implementation of LinkedList collect: - Your're right, there is none, it's inherited by SequenceableCollection. Looking through this code, I discovered that it builds a LinkedList of the same size and then uses the at: and at:put: selector to copy the transformed values form the first list to the second.

Knowing that at: and at:put: have O(n) complexity for linked lists, this makes collect: an O(n^2) operation. On the other hand, this could easily changed into O(n) by implementing collect: for LinkedList:

collect: aBlock�

"Evaluate aBlock with each of the receiver's elements as the argument. �

Collect the resulting values into a collection like the receiver. Answer �

the new collection."

| newCollection |

newCollection := self species new.

self do:

[:val |

newCollection add: (aBlock value: val)].

^ newCollection

I profiled this using:

x := LinkedList new.

1 to: 10000 do: [:n |x add: n].

TimeProfileBrowser onBlock: [ x collect: [:i | i] ]

and saw a improvement of: 795msec (old) vs. 6msec (new).

I wonder therefore, if LinkedList is just seldomly used (in Java i.e. nearly all lists use ArrayList nowadays)? Or would the system benefit from this improvement? I could then look through the other methods (collect:from:to: et. al.) and provide a patch.

best regards + thank's for creating such a beautiful system

Andreas Haufler