Jason House wrote:
Walter Bright Wrote:
bearophile wrote:
Walter Bright:
Executive summary: pure functions and immutable data structures
help manage program complexity.
At the moment in D there aren't many immutable data structures
available, but of course they can be written. Such data
structures often put the GC under some/high pressure. I don't
know if the current D GC is able to cope.
I don't understand your comment. With immutable being transitive,
any data structure can be made immutable. The GC doesn't care if a
data structure is immutable or not, I don't see how that affects
its operation.
Think about what happens when you want to mutate an immutable data
structure. You must create one or more new objects. That increases
the number of objects for the GC to handle
On the other hand, immutability means that diverse data structures can
share parts of them, reducing the number of objects. I find that
immutable strings means my programs allocate far fewer strings, as it is
no longer necessary to defensively make copies "just in case" something
else changes them.
I've been thinking of transitioning dmd's semantic analysis to using
immutable data structures because it will reduce allocations, not
increase them.
