Edward Kmett ekmett at
Fri Aug 21 00:29:34 UTC 2015

Would it be possible to add unsafe primops to add Array# and SmallArray#
entries to an ArrayArray#? The fact that the ArrayArray# entries are all
directly unlifted avoiding a level of indirection for the containing
structure is amazing, but I can only currently use it if my leaf level data
can be 100% unboxed and distributed among ByteArray#s. It'd be nice to be
able to have the ability to put SmallArray# a stuff down at the leaves to
hold lifted contents.

I accept fully that if I name the wrong type when I go to access one of the
fields it'll lie to me, but I suppose it'd do that if i tried to use one of
the members that held a nested ArrayArray# as a ByteArray# anyways, so it
isn't like there is a safety story preventing this.

I've been hunting for ways to try to kill the indirection problems I get
with Haskell and mutable structures, and I could shoehorn a number of them
into ArrayArrays if this worked.

Right now I'm stuck paying for 2 or 3 levels of unnecessary indirection
compared to c/java and this could reduce that pain to just 1 level of
unnecessary indirection.

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