[m-users.] Higher-order predicates and functions and equivalence types.

[Volker Wysk]

Am Samstag, dem 28.08.2021 um 13:47 +0200 schrieb Volker Wysk:
> Am Samstag, dem 28.08.2021 um 09:00 +0200 schrieb Volker Wysk:
> > Am Freitag, dem 27.08.2021 um 20:26 +0100 schrieb Sean Charles
> > (emacstheviking):
> > > Hi,
> > > 
> > > I have a type definition like this:
> > > 
> > > :- type tcon
> > >     --->    tcon(
> > >                 options  :: felt_options,
> > >                 output   :: list(rop),
> > >                 warnings :: lserror,
> > >                 errors   :: lserror,
> > >                 render   :: pred(instruction::in, string::in, string::out) is semidet
> > >                 % ENV[] stack can go in here too
> > >             ).
> > > 
> > > The `render` field, I wanted to be able to code this something like:
> > > 
> > >     render :: foo
> > > 
> > > where foo would have been defined as
> > > 
> > > :- type foo = (pred(instruction::in, string::in, string::out) is semidet).
> > 
> > I'm not sure, but you have the type and modes in your type "foo". I think
> > you can only have the type in a type synonym. You also need to equal signs.
> 
> Again:
> 
> You have specified the types and the modes of the predicate arguments in
> your "foo" type synonym. There's also the determinism category. I think, you
> can only specify the types in a ":- type" statement. 

Come to think of it, I now see that I'm wrong with that. Sorry.

Volker
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