Re: pldoc: how to specify predicates with arguments unbound.

On 16/09/2014, at 10:48 PM, Kuniaki Mukai wrote:

> 
> I wish someone will introduce powerful "mode inference" system 
> to SWI-Prolog in the near future. 

If you want a logic programming language in which the compiler
understands modes, Mercury exists and has been in use for quite
a few years now.  I urge anyone who wants modes in SWI Prolog
to do some serious programming in Mercury for a bit to find out
what it's like.

Modes of course express a programmer's intentions.
When you write Prolog, it's far from unusual to have
a predicate which *ought* to be logically invertible
but does not in fact *work* when used in modes you did
not think of.

What's really sad is when an interface *could* be implemented
in a multi-modal way but wasn't because the programmer never
thought of it.