Re: Suggestions to remove one alist's members from another

[Davis Herring]

> If not, my thought is this: when the list was over some size
> I'd determine experimentally, it would instead build a hash
> table from in-list and hit the not-alist against that.  When
> complete it would unfortunately require a second pass
> through the in-alist to return it maintaining the original
> order.

Why not build a hash table (of the cars of the elements) from not-alist
instead?  Then you can just walk in-alist, skipping elements that are in
the hash (that is, whose cars are in it) and adding the rest to out-alist
and (their cars to) the hash.

Davis

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