Arc Forum | In that case, you want the zap macro: (zap join x '(a b c)) zap turns into, mo...

Arc Forum

1 point by absz 5765 days ago | link | parent

In that case, you want the zap macro:

  (zap join x '(a b c))

zap turns into, more or less,

  (= x (join x '(a b c)))

Its signature is (op place . args), so all the arguments are optimized.

However, we do need naming conventions; zap, though multipurpose, is still not completely general. And there are no good ones, unfortunately.

1 point by stefano 5764 days ago | link

The problem is that when using join with zap you need to cons a lot of memory, while a destructive join would not cons up memory, it would just traverse the list setting the right cdrs. Probably the expression "recycling operations" describes better what I wanted to say, because operations such as nconc reuse the memory of their arguments.

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