Subj : Re: Compiler and an interpreter
To   : comp.programming
From : Jon Harrop
Date : Fri Aug 05 2005 06:31 pm

Gerry Quinn wrote:
> In article <1123159636.278503.19720@g43g2000cwa.googlegroups.com>,
> robert.thorpe@antenova.com says...
>> Gerry Quinn wrote:
> 
>> > Either takes seconds to write.
>  
>> But on a larger scale writing more of the OCaml is quicker.  It may
>> take you 30 seconds to write the above, but it may take Jon 10 seconds
>> to write his.  It all adds up.
> 
> Given that in either case one could write thousands of LOC in a day if
> this were the bottleneck, I don't think it's a real issue.

The real issue is that the ratio of OCaml to C++ code size increases as the
absolutely code size increases. On 100 LOC programs I typically find C++ to
be twice as verbose. On 1,000 LOC programs C++ is more like 5x as verbose.
The largest project of my own projects replaced ~100kLOC of C++ with 4kLOC
of OCaml.

>> I'm pretty sure you can do this in C++ anyway, with "transform".
> 
> What I wrote is a C++ cliche that will be equally recognisable.

As your "cliche" fails to factor out a HOF it is necessarily less powerful.

>> So, what would be really interesting to know is:
>> * Could one write a more concise C++ version, regardless of efficiency
>> * Could one write a faster C++ version, regardless of conciseness
>> * Could both be done
> 
> My guess is that the second could probably be done, but not the first.
> C++ is designed so you can go as low-level as C to please the hardware,
> so it should be feasible to write a very fast program.

That is a common misconception that only applies to trivial problems. For
anything non-trivial, you need a HLL to get good performance.

>> It's not that complex, though it's certainly more complex than average.
>>  Perhaps one function in a twenty a programmer would have to write
>> would be that complex, I'd guess.
> 
> I doubt that, unless he really hates short functions!  Maybe we could
> say that writing such functions, even if they are one in a hundred,
> might well take a significant fraction of the programmer's time, if the
> task is math-intensive.

What exactly do you mean by "math intensive", e.g. are algorithms and data
structures "math"?

-- 
Dr Jon D Harrop, Flying Frog Consultancy
http://www.ffconsultancy.com

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