Older blog entries for redi (starting at number 238)

fzort, here's a better response from a linguist in my family, my guess was probably wrong :)

I think it's an evolution such as takes place in any language in different ways. In English, I suspect this particular one comes from the mix of different other-language speakers learning English and the habit has spread because of modern media diffusion.

It is interstingly not a complete evolution. With two prepositions involved, it was originally 'tell it to me', just as it still is 'explain it to me'. The incompleteness can be felt/seen if you say something like 'I told him it'. There's a slightly clumsy feel, to me at least, in the use of the two pronouns side by side.

Consider also that English is unusual in having two words for what is often only one in other languages - to say and to tell, for dire in French. You wouldn't say 'Say it me' or 'Say me it'. Equally, the indirect object//dative case form applies to speak/talk//parler. 'Speak French to him', or 'talk sense to me' are the ways we say it. Not 'talk me sense' or 'speak him French'. So it is 'tell' that seems to have undergone this semi-evolution, why I cannot be sure. Or really I haven't a clue. But it doesn't have nowt to do with Latin vs Germanic etymology.

Hi, fzort! I don't even see all those diaries from proclus thanks to the rating system.

Sorry, parsing English is even more ambiguous than parsing C++.

The transitive verb "explain" can have a direct object (the thing being explained) and an indirect object (the recipient of the explanation.) "She explained me" makes "me" the direct object, that is, the thing being explained. "She explained something to me" has "something" as the direct object and "me" as the indirect object. "Tell" can be used the same way: "She told something to me" is correct, but so is "she told me something" -- but that's not the case for "explain." I'm not sure why but the difference might be because "explain" comes from Latin and "tell" comes from Anglo-Saxon, which have different grammar.

ncm, I would really really like that browser feature too.
2 Mar 2011 (updated 2 Mar 2011 at 15:24 UTC) »

In C++ foldr is pronounced std::accumulate and map is pronounced std::transform.

I don't think we have a word for unfold, but I guess I'd say it like this:


template<class OutIt, class P, class F, class G, class T>
size_t
unfold(OutIt result, P stop, F f, G g, T x)
{
    if (stop(x))
        return 0;
    *result = f(x);
    return 1 + unfold(++result, stop, f, g, g(x));
}

Edit: hmm, no I wouldn't, it's unspecified whether g or g(x) gets evaluated first, which matters if G is stateful (which it shouldn't be, but have ever tried telling a C++ programmer they shouldn't use a sharp object?) A workaround would be to pass stateful functors in by reference, e.g. using a reference wrapper such as boost::ref or std::ref but it'd be nice if that wasn't needed. I'll have to think about that further ...

audriusa please fix your diary entry, it's fscking up the following entry on recentlog
20 Jan 2011 (updated 20 Jan 2011 at 10:52 UTC) »
The Empire Strikes Back

Like chalst, I'm pleased there are still some interesting unsyndicated diaries in recentlog. If only they weren't massively outnumbered by the new spam accounts created every day.

17 Jan 2011 (updated 19 Jan 2011 at 09:40 UTC) »

kill the spammer below this post [he got killed, but despite blocking his IP range he's back again]

someone patch mod_virgule to reject all accounts from repeat spammer "tarunyadavseo" - please click on his name in "New advogato members" and mark his account as spam. Then find him and set fire to him.

6 Jan 2011 (updated 6 Jan 2011 at 20:08 UTC) »
Adventures in C++ compiler land

I've ventured into the g++ front end a couple of times recently (I usually only touch libstdc++ code) trying to fix some bugs. I haven't managed to get my patches reviewed, but as stage 3 has ended I'll have to wait until 4.6 is branched and then try to get them into 4.7

More clang bangin'

One of the goals/features of Clang/LLVM is faster compile times than GCC, so I think something's very wrong with my build (which I configured as a "Release+Asserts build"):


$ wc -l src/Order.cc
4107 src/Order.cc
$ time make CXX=g++ objs/Order.o
...
real    0m8.993s
user    0m8.483s
sys     0m0.339s
$ time make CXX=g++ CXXFLAGS="-O2 -DNDEBUG" objs/Order.o
...
real    0m12.111s
user    0m11.999s
sys     0m0.309s
$ time make CXX=clang++ objs/Order.o
...
real    2m11.608s
user    2m7.475s
sys     0m0.260s
$ time make CXX=clang++ CXXFLAGS="-O2 -DNDEBUG" objs/Order.o
...
real    17m22.577s
user    17m21.589s
sys     0m0.377s

Yes, that really did take 17 minutes at 100% CPU (on a 2.93GHz Xeon X5570) compared to 12 seconds for GCC.

One of the things I really like is that most of GCC's command-line options are supported. so I used -ftime-report to see where all that time is spent, but all the detailed stats are for the code generation stages, which is the only bit that isn't slow!

---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name ---
137.5871 ( 50.6%) 0.2380 ( 67.8%) 137.8250 ( 50.6%) 138.0570 ( 50.6%) Clang front-end timer
131.2420 ( 48.2%) 0.0610 ( 17.4%) 131.3030 ( 48.2%) 131.3707 ( 48.2%) LLVM IR Generation Time
3.1755 ( 1.2%) 0.0520 ( 14.8%) 3.2275 ( 1.2%) 3.2308 ( 1.2%) Code Generation Time
272.0046 (100.0%) 0.3509 (100.0%) 272.3556 (100.0%) 272.6585 (100.0%) Total

That was with a build from subversion a few weeks ago (trunk 121966) so I updated and got sensible times, although the optimised build is still slower than I expected:


$ time make CXX=clang++ objs/Order.o
...
real    0m7.380s
user    0m6.674s
sys     0m0.471s
$ time make CXX=clang++ CXXFLAGS="-O2 -DNDEBUG" objs/Order.o
...
real    0m17.667s
user    0m17.131s
sys     0m0.309s

I don't remember the earlier build being so slow a few weeks ago, so maybe some gremlins came and moved the files to a really slow bit of the filesystem over Christmas.

Using Clang on a large codebase did find a few bugs which GCC and Sun CC didn't object to (one notable feature is that clang++ found errors in templates which were never instantiated, which even EDG didn't find) and I also found a bug in clang, but one of the main reasons I wanted to try it was the static analyzer. Unfortunately it only works for C and Obj-C and trying to analyze C++ fails miserably. I guess I'll wait and try it again at a later date.

24 Dec 2010 (updated 3 May 2011 at 20:30 UTC) »

If you want to build gcc from source, for any released version since 3.0 (or something equally ancient,) or a recent snapshot, use this makefile

config-gcc.mk

download it, put it in a new dir, and run gmake -f config-gcc.mk, then do what it tells you to do

You can do exciting things such as

gmake -f config-gcc.mk GCC_VERSION=4.6-20101218 MPFR_VERSION=3.0.1 LOCAL_SRC=$HOME/Downloads

to build a specific version (including snapshots) with specific versions of the GMP, MPFR and MPC prerequisites, and to use tarballs from a local directory if you've already downloaded them.

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