Re: Exquisite code samples
On Tuesday, 10 July 2012 at 09:24:42 UTC, Don Clugston wrote: On 10/07/12 09:49, renoX wrote: On Monday, 9 July 2012 at 11:40:37 UTC, Gor Gyolchanyan wrote: [cut] You're right. This is a bit advanced code sample, which uses templates,template constraints, contract programming among syntax advantages of D. Hum it show the power of D sure, but IMHO it also show its syntax deficiencies.. For me this real[d] bezier(size_t d, Number)(Number[d][] p, Number t) if(d 1 isFloatingPoint!Number) is difficult to read, and a better syntax would be: real[d] bezier!(size_t d d 1, Number isFloatingPoint!Number)(Number[d][] p, Number t) The template parameter would be indicated in a !() (as in a call), and the template constraints inside the template parameter: this way the template parameters are clearly indicated and separated from the function parameter. renoX Well it used to work vaguely in that way, but it gets very ugly once you leave the simplest cases. Even that one you've listed is hard for me to read. IMHO, the normal way is even harder to read.. And the idea that constraints apply to individual parameters is wrong. If you have a constraint that depends on two template parameters, where do you put it? int bezier (int A, int B)(int t) if ( A + B == 10 ) How about: int bezier!(int A, int B; A + B == 10)(int t) ? I think that grouping together template parameters and constraints helps the readability YMMV. BR, renoX PS: Sorry for the multiple posting, the posting didn't seem to work so I retried..
Re: Exquisite code samples
On Monday, 9 July 2012 at 11:40:37 UTC, Gor Gyolchanyan wrote:
On Mon, Jul 9, 2012 at 3:30 PM, Paulo Pinto
pj...@progtools.org wrote:
On Monday, 9 July 2012 at 11:16:45 UTC, Gor Gyolchanyan wrote:
I've put together a code sample, which could demonstrate the
awesome power
of D when it comes to getting good results very quickly and
safely.
Perhaps
it could end up on display for newcomers:
import std.traits;
/// Returns the t-th point on the bezier curve, defined by
non-empty set p
of d-dimensional points, where t : [0, 1] and d 1.
real[d] bezier(size_t d, Number)(Number[d][] p, Number t)
if(d 1 isFloatingPoint!Number)
in
{
assert(p.length 0);
assert(t = 0.0L t = 1.0L);
}
body
{
return p.length 1 ? (1 - t) * p[0..$-1].bezier(t) + t *
p[1..$].bezier(t) : p[0];
}
/// Returns k unidistant points on the bezier curve, defined
by non-empty
set p of d-dimensional points, where k 0 and d 1.
real[d][] bezier(size_t d, Number)(Number[d][] p, size_t k)
if(d 1 isFloatingPoint!Number)
in
{
assert(p.length 0);
assert(k 0);
}
body
{
Number[d][] result = new Number[d][k];
foreach(i; 0..k)
result[k] = p.bezier(i * (1.0L / k));
return result;
}
I would not show this to newcomers, as they would probably go
running for
Go.
This type of code is quite nice and the reason why I think I
am better
served with D than Go, but newcomers without strong generic
programming
background in other languages might get scared.
--
Paulo
You're right. This is a bit advanced code sample, which uses
templates,
template constraints, contract programming among syntax
advantages of D.
At least, with a main() and an input, it would be a bit more
interesting and illustrative of the modeling power of D than
the examples of the http://dlang.org/index.html home page, which
are stupid and mostly don't work at all. (even the simplest
example gives the ridiculous result of 895 until one manually
breaks the input text with carriage returns).
Re: Exquisite code samples
On Monday, 9 July 2012 at 11:40:37 UTC, Gor Gyolchanyan wrote: [cut] You're right. This is a bit advanced code sample, which uses templates,template constraints, contract programming among syntax advantages of D. Hum it show the power of D sure, but IMHO it also show its syntax deficiencies.. For me this real[d] bezier(size_t d, Number)(Number[d][] p, Number t) if(d 1 isFloatingPoint!Number) is difficult to read, and a better syntax would be: real[d] bezier!(size_t d d 1, Number isFloatingPoint!Number)(Number[d][] p, Number t) The template parameter would be indicated in a !() (as in a call), and the template constraints inside the template parameter: this way the template parameters are clearly indicated and separated from the function parameter. renoX
Re: Exquisite code samples
On Monday, 9 July 2012 at 11:40:37 UTC, Gor Gyolchanyan wrote: [cut] You're right. This is a bit advanced code sample, which uses templates,template constraints, contract programming among syntax advantages of D. Hum it show the power of D sure, but IMHO it also show its syntax deficiencies.. For me this real[d] bezier(size_t d, Number)(Number[d][] p, Number t) if(d 1 isFloatingPoint!Number) is difficult to read, and a better syntax would be: real[d] bezier!(size_t d d 1, Number isFloatingPoint!Number)(Number[d][] p, Number t) or maybe: real[d] bezier!(size_t d, Number; d 1 isFloatingPoint!Number)(Number[d][] p, Number t) The template parameter would be indicated in a !() (as in a call), and the template constraints inside the template parameter: this way the template parameters are clearly indicated and separated from the function parameter. renoX
Re: Exquisite code samples
On 10/07/12 09:49, renoX wrote: On Monday, 9 July 2012 at 11:40:37 UTC, Gor Gyolchanyan wrote: [cut] You're right. This is a bit advanced code sample, which uses templates,template constraints, contract programming among syntax advantages of D. Hum it show the power of D sure, but IMHO it also show its syntax deficiencies.. For me this real[d] bezier(size_t d, Number)(Number[d][] p, Number t) if(d 1 isFloatingPoint!Number) is difficult to read, and a better syntax would be: real[d] bezier!(size_t d d 1, Number isFloatingPoint!Number)(Number[d][] p, Number t) The template parameter would be indicated in a !() (as in a call), and the template constraints inside the template parameter: this way the template parameters are clearly indicated and separated from the function parameter. renoX Well it used to work vaguely in that way, but it gets very ugly once you leave the simplest cases. Even that one you've listed is hard for me to read. And the idea that constraints apply to individual parameters is wrong. If you have a constraint that depends on two template parameters, where do you put it? int bezier (int A, int B)(int t) if ( A + B == 10 )
Re: Exquisite code samples
On Monday, 9 July 2012 at 11:40:37 UTC, Gor Gyolchanyan wrote: [cut] You're right. This is a bit advanced code sample, which uses templates, template constraints, contract programming among syntax advantages of D. Hum it shows the power of D sure, but IMHO it also shows its syntax deficiencies.. For me this real[d] bezier(size_t d, Number)(Number[d][] p, Number t) if(d 1 isFloatingPoint!Number) is difficult to read, and a better syntax would be for example: real[d] bezier!(size_t d d 1, Number isFloatingPoint!Number)(Number[d][] p, Number t) or: real[d] bezier!(size_t d, Number; d 1 isFloatingPoint!Number)(Number[d][] p, Number t) The template parameter would be indicated in a !() (as in a call), and the template constraints inside the template parameter renoX
Re: Exquisite code samples
It is suppose to compile?
I get:
t4.d(16): Error: incompatible types for ((cast(real)1 - t) *
(bezier(p[0u..__dollar - 1u],t))): 'real' and 'real[3u]'
t4.d(16): Error: incompatible types for ((t) *
(bezier(p[1u..__dollar],t))): 'real' and 'real[3u]'
t4.d(43): Error: template instance t4.bezier!(3u,real) error instantiating
On Mon, Jul 9, 2012 at 6:16 AM, Gor Gyolchanyan
gor.f.gyolchan...@gmail.com wrote:
I've put together a code sample, which could demonstrate the awesome power
of D when it comes to getting good results very quickly and safely. Perhaps
it could end up on display for newcomers:
import std.traits;
/// Returns the t-th point on the bezier curve, defined by non-empty set p
of d-dimensional points, where t : [0, 1] and d 1.
real[d] bezier(size_t d, Number)(Number[d][] p, Number t)
if(d 1 isFloatingPoint!Number)
in
{
assert(p.length 0);
assert(t = 0.0L t = 1.0L);
}
body
{
return p.length 1 ? (1 - t) * p[0..$-1].bezier(t) + t *
p[1..$].bezier(t) : p[0];
}
/// Returns k unidistant points on the bezier curve, defined by non-empty
set p of d-dimensional points, where k 0 and d 1.
real[d][] bezier(size_t d, Number)(Number[d][] p, size_t k)
if(d 1 isFloatingPoint!Number)
in
{
assert(p.length 0);
assert(k 0);
}
body
{
Number[d][] result = new Number[d][k];
foreach(i; 0..k)
result[k] = p.bezier(i * (1.0L / k));
return result;
}
--
Bye,
Gor Gyolchanyan.
Re: Exquisite code samples
On Monday, 9 July 2012 at 11:16:45 UTC, Gor Gyolchanyan wrote:
I've put together a code sample, which could demonstrate the
awesome power
of D when it comes to getting good results very quickly and
safely. Perhaps
it could end up on display for newcomers:
import std.traits;
/// Returns the t-th point on the bezier curve, defined by
non-empty set p
of d-dimensional points, where t : [0, 1] and d 1.
real[d] bezier(size_t d, Number)(Number[d][] p, Number t)
if(d 1 isFloatingPoint!Number)
in
{
assert(p.length 0);
assert(t = 0.0L t = 1.0L);
}
body
{
return p.length 1 ? (1 - t) * p[0..$-1].bezier(t) + t *
p[1..$].bezier(t) : p[0];
}
/// Returns k unidistant points on the bezier curve, defined by
non-empty
set p of d-dimensional points, where k 0 and d 1.
real[d][] bezier(size_t d, Number)(Number[d][] p, size_t k)
if(d 1 isFloatingPoint!Number)
in
{
assert(p.length 0);
assert(k 0);
}
body
{
Number[d][] result = new Number[d][k];
foreach(i; 0..k)
result[k] = p.bezier(i * (1.0L / k));
return result;
}
I would not show this to newcomers, as they would probably go
running for Go.
This type of code is quite nice and the reason why I think I am
better served with D than Go, but newcomers without strong
generic programming background in other languages might get
scared.
--
Paulo
Re: Exquisite code samples
On Mon, Jul 9, 2012 at 3:30 PM, Paulo Pinto pj...@progtools.org wrote:
On Monday, 9 July 2012 at 11:16:45 UTC, Gor Gyolchanyan wrote:
I've put together a code sample, which could demonstrate the awesome power
of D when it comes to getting good results very quickly and safely.
Perhaps
it could end up on display for newcomers:
import std.traits;
/// Returns the t-th point on the bezier curve, defined by non-empty set p
of d-dimensional points, where t : [0, 1] and d 1.
real[d] bezier(size_t d, Number)(Number[d][] p, Number t)
if(d 1 isFloatingPoint!Number)
in
{
assert(p.length 0);
assert(t = 0.0L t = 1.0L);
}
body
{
return p.length 1 ? (1 - t) * p[0..$-1].bezier(t) + t *
p[1..$].bezier(t) : p[0];
}
/// Returns k unidistant points on the bezier curve, defined by non-empty
set p of d-dimensional points, where k 0 and d 1.
real[d][] bezier(size_t d, Number)(Number[d][] p, size_t k)
if(d 1 isFloatingPoint!Number)
in
{
assert(p.length 0);
assert(k 0);
}
body
{
Number[d][] result = new Number[d][k];
foreach(i; 0..k)
result[k] = p.bezier(i * (1.0L / k));
return result;
}
I would not show this to newcomers, as they would probably go running for
Go.
This type of code is quite nice and the reason why I think I am better
served with D than Go, but newcomers without strong generic programming
background in other languages might get scared.
--
Paulo
You're right. This is a bit advanced code sample, which uses templates,
template constraints, contract programming among syntax advantages of D.
--
Bye,
Gor Gyolchanyan.
Re: Exquisite code samples
This type of code is quite nice and the reason why I think I am better served with D than Go, but newcomers without strong generic programming background in other languages might get scared. -- Paulo And for people that have no such background the advantages need some explanation. It's not obvious, but with some explanation it is a good example.
