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digitalmars.D.learn - Expression tuples

reply simendsjo <simen.endsjo pandavre.com> writes:
http://www.digitalmars.com/d/2.0/tuple.html

// this example fails
Tuple!(3, 7, 'c')

typecons.d(298): Error: static assert "Attempted to instantiate Tuple
with an invalid argument: 3"

Even this fails:
alias Tuple!(0) T;

Is Tuple only meant to store types or named types?
Mar 16 2011
next sibling parent "Simen kjaeraas" <simen.kjaras gmail.com> writes:
On Wed, 16 Mar 2011 21:07:08 +0100, simendsjo <simen.endsjo pandavre.com>  
wrote:

 http://www.digitalmars.com/d/2.0/tuple.html

 // this example fails
 Tuple!(3, 7, 'c')

 typecons.d(298): Error: static assert "Attempted to instantiate Tuple
 with an invalid argument: 3"

 Even this fails:
 alias Tuple!(0) T;

 Is Tuple only meant to store types or named types?

std.typecons.Tuple is a value type, mostly like those tuples you find in other languages like Python, Haskell, etc. What you are likely looking for is std.typetuple.Typetuple. -- Simen
Mar 16 2011
prev sibling next sibling parent "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Wed, 16 Mar 2011 16:28:48 -0400, Simen kjaeraas  
<simen.kjaras gmail.com> wrote:

 On Wed, 16 Mar 2011 21:07:08 +0100, simendsjo  
 <simen.endsjo pandavre.com> wrote:

 http://www.digitalmars.com/d/2.0/tuple.html

 // this example fails
 Tuple!(3, 7, 'c')

 typecons.d(298): Error: static assert "Attempted to instantiate Tuple
 with an invalid argument: 3"

 Even this fails:
 alias Tuple!(0) T;

 Is Tuple only meant to store types or named types?

std.typecons.Tuple is a value type, mostly like those tuples you find in other languages like Python, Haskell, etc. What you are likely looking for is std.typetuple.Typetuple.

If you read that page he is referring to, it seems like you should be able to create an expression tuple. I don't know if that works with std.typecons.tuple. In fact, I don't think I've ever seen some of the stuff that's in that page, especially the mixed type+expression tuple. Is it valid? -Steve
Mar 16 2011
prev sibling next sibling parent reply "Simen kjaeraas" <simen.kjaras gmail.com> writes:
On Wed, 16 Mar 2011 21:51:37 +0100, Steven Schveighoffer  
<schveiguy yahoo.com> wrote:

 On Wed, 16 Mar 2011 16:28:48 -0400, Simen kjaeraas  
 <simen.kjaras gmail.com> wrote:

 On Wed, 16 Mar 2011 21:07:08 +0100, simendsjo  
 <simen.endsjo pandavre.com> wrote:

 http://www.digitalmars.com/d/2.0/tuple.html



 If you read that page he is referring to, it seems like you should be  
 able to create an expression tuple.

 I don't know if that works with std.typecons.tuple.

 In fact, I don't think I've ever seen some of the stuff that's in that  
 page, especially the mixed type+expression tuple.  Is it valid?

Oh, absolutely. Given that you use the Tuple template declared at the top of the page. However, I would recommend the page be rewritten so as not to cause confusion between that and std.typecons.Tuple. -- Simen
Mar 16 2011
parent Jonathan M Davis <jmdavisProg gmx.com> writes:
On Wednesday, March 16, 2011 14:43:20 Steven Schveighoffer wrote:
 On Wed, 16 Mar 2011 17:31:06 -0400, Simen kjaeraas
 
 <simen.kjaras gmail.com> wrote:
 On Wed, 16 Mar 2011 21:51:37 +0100, Steven Schveighoffer
 
 <schveiguy yahoo.com> wrote:
 On Wed, 16 Mar 2011 16:28:48 -0400, Simen kjaeraas
 
 <simen.kjaras gmail.com> wrote:
 On Wed, 16 Mar 2011 21:07:08 +0100, simendsjo
 
 <simen.endsjo pandavre.com> wrote:
 http://www.digitalmars.com/d/2.0/tuple.html


If you read that page he is referring to, it seems like you should be able to create an expression tuple. I don't know if that works with std.typecons.tuple. In fact, I don't think I've ever seen some of the stuff that's in that page, especially the mixed type+expression tuple. Is it valid?

Oh, absolutely. Given that you use the Tuple template declared at the top of the page. However, I would recommend the page be rewritten so as not to cause confusion between that and std.typecons.Tuple.

As I was confused there and thought we were talking about std.typecons.Tuple, I wholeheartedly agree :) Now I am concerned, this looks like an oxymoron: TypeTuple!(1, 2, 3) Should we think about changing the name of std.typetuple.TypeTuple since it can clearly contain expressions as well as types? I would actually argue that TypeTuple should be called Tuple, and Tuple be called ValueTuple or something, but I understand we probably cannot do that at this point...

Regardless of whether TypeTuple can hold values or not, it really doesn't make sense to call it a tuple in the general sense, since it's always flat and cannot hold other tuples. IIRC, Andrei had a good suggestion for what to rename TypeTuple to, but unfortunately, I don't recall what it was at the moment. Regardless, I think that TypeTuple _should_ be renamed. It's far too easy to confuse it with Tuple. However, Tuple is definitely more of a tuple than TypeTuple is. - Jonathan M Davis
Mar 16 2011
prev sibling next sibling parent "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Wed, 16 Mar 2011 17:31:06 -0400, Simen kjaeraas  
<simen.kjaras gmail.com> wrote:

 On Wed, 16 Mar 2011 21:51:37 +0100, Steven Schveighoffer  
 <schveiguy yahoo.com> wrote:

 On Wed, 16 Mar 2011 16:28:48 -0400, Simen kjaeraas  
 <simen.kjaras gmail.com> wrote:

 On Wed, 16 Mar 2011 21:07:08 +0100, simendsjo  
 <simen.endsjo pandavre.com> wrote:

 http://www.digitalmars.com/d/2.0/tuple.html



 If you read that page he is referring to, it seems like you should be  
 able to create an expression tuple.

 I don't know if that works with std.typecons.tuple.

 In fact, I don't think I've ever seen some of the stuff that's in that  
 page, especially the mixed type+expression tuple.  Is it valid?

Oh, absolutely. Given that you use the Tuple template declared at the top of the page. However, I would recommend the page be rewritten so as not to cause confusion between that and std.typecons.Tuple.

As I was confused there and thought we were talking about std.typecons.Tuple, I wholeheartedly agree :) Now I am concerned, this looks like an oxymoron: TypeTuple!(1, 2, 3) Should we think about changing the name of std.typetuple.TypeTuple since it can clearly contain expressions as well as types? I would actually argue that TypeTuple should be called Tuple, and Tuple be called ValueTuple or something, but I understand we probably cannot do that at this point... -Steve
Mar 16 2011
prev sibling parent "Simen kjaeraas" <simen.kjaras gmail.com> writes:
On Wed, 16 Mar 2011 22:43:20 +0100, Steven Schveighoffer  
<schveiguy yahoo.com> wrote:

 Now I am concerned, this looks like an oxymoron:

 TypeTuple!(1, 2, 3)

 Should we think about changing the name of std.typetuple.TypeTuple since  
 it can clearly contain expressions as well as types?  I would actually  
 argue that TypeTuple should be called Tuple, and Tuple be called  
 ValueTuple or something, but I understand we probably cannot do that at  
 this point...

Such has been discussed before. std.typecons.Tuple should also have a reasonably terse name, a virtue I feel ValueTuple does not fulfill. The problem is that those things contained in a std.typetuple.TypeTuple are so diverse, and thus hard to put in category. FreeTuple? TupleList? AnyTuple? AllTuple? Anyways, I'm off to sleep. Good... Well, I guess it's day to most of you on the other side of the pond. Good day, then. :p -- Simen
Mar 16 2011