Neil Mitchell wrote:
Hi Isaac,
Or will I have to
#define UTopen (#
#defined UTclose #)
and (UTopen x, y UTclose)
Yuk! There is a ticket on adding a prefix form of (#,#), which is
currently lacking. Perhaps adding that first, then moving to the
unboxed thingy would be best. Also your use of # in a CPP macro may
confuse various CPP stuff in GHC.
UTopen/UTclose are no worse than the macros for unboxed string literals
that GHC already uses:
#define SLIT(x) (FS.mkLitString# (x#))
#define FSLIT(x) (FS.mkFastString# (x#))
(although I wish it didn't even use those! Is there any way to use RULES
or optimization for the same effect?)
and then I would probably have to use separate macros for different
tuple sizes, since CPP doesn't like commas. Or use UT(COMMA COMMA) for a
three-size tuple. `TUPLE3 x y z` doesn't look so bad though -- just
like a constructor, which it could be otherwise; data TUPLE3 a b c =
TUPLE3 a b c
I'd also be shocked if it turns out that unboxed types make that much
of a difference. They will make a difference in library functions
(called a lot), or hot-spots, but in general they only add a constant
improvement. Of course, numbers are better than speculation - and
would be interesting in their own right!
could be, I guess I'll test. They're only used in the gratuitous way I
described in a few places, so I was guessing it was intentional and
there might have been a performance bottleneck...
oh wait, I remember why... you can't return a boxed tuple of unboxed
values. Which might actually be important in some places, like
utils/Encoding:
------------------------------------------------------------------
-- UTF-8
-- We can't write the decoder as efficiently as we'd like without
-- resorting to unboxed extensions, unfortunately. I tried to write
-- an IO version of this function, but GHC can't eliminate boxed
-- results from an IO-returning function.
--
-- We assume we can ignore overflow when parsing a multibyte character here.
-- To make this safe, we add extra sentinel bytes to unparsed UTF-8
sequences
-- before decoding them (see StringBuffer.hs).
{-# INLINE utf8DecodeChar# #-}
utf8DecodeChar# :: Addr# -> (# Char#, Addr# #)
Isaac
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