[m-dev.] foreign type syntax

[Peter Ross]

On Thu, Oct 25, 2001 at 10:13:57PM +1000, Fergus Henderson wrote:
> On 25-Oct-2001, Tyson Dowd <trd at cs.mu.OZ.AU> wrote:
> > We propose adding a foreign_type pragma, which allows you to define a
> > Mercury type as being equivalent to a foreign language type. 
> 
> What happens if the foreign language type doesn't fit in a single word?
> Will the Mercury compiler automatically box/unbox it, like it does for `float'?
> 
> > Currently the syntax is:
> > 
> > :- pragma foreign_type(xmldoc, 'System__Xml__XmlDocument', il("System.Xml")).
> > 
> > This defines a new Mercury type "xmldoc", which is defined to be the
> > same as the type System.Xml.XmlDocument in the IL backend, which can be
> > found in the assembly System.Xml.
> > 
> > This syntax is a bit broken, but it helps us establish what has to be
> > covered by an improved syntax:
> > 
> > We must specify 
> > 	- the name of the Mercury type
> > 	- the name of the foreign type
> > 	- the backend(s) to which this mapping applies
> 
> Why do you say "backends" rather than "languages" here?
> 
See answer below.

> 
> > Finally, I'm still not sure about what to do about namespace nested
> > names.  System__Xml__XmlDocument is a bit long, but the idea is that
> > it just uses Mercury's nested module naming system, so when we switch to
> > "." we can just use "." instead.  So I guess it will be nicer in future.
> 
> I think it would be nicer to just use whatever syntax the foreign language
> uses.
>  
On the IL backend, there is no language as such.  This type name might
need to be used in one or all of IL code, Managed C++, C# and possibly
any other IL targetting language we decide to foreign_proc enable.

So in keeping with the spirit of the IL backend, you should represent
the name as appropiate in Mercury in this case using __ as the
namespace seperator.

However on all the other backends, you may want to represent it how that
backend does.
--------------------------------------------------------------------------
mercury-developers mailing list
Post messages to:       mercury-developers at cs.mu.oz.au
Administrative Queries: owner-mercury-developers at cs.mu.oz.au
Subscriptions:          mercury-developers-request at cs.mu.oz.au
--------------------------------------------------------------------------