[m-rev.] for review: better error messages for lambda exprs

[Julien Fischer]

On Tue, 17 May 2016, Mark Brown wrote:

>> +    ; Name = "or"                   % goal
>> +    ; Name = "and"                  % goal
>> +    ; Name = "try"                  % goal
>> +    ; Name = "@"                    % goal
>> +    ; Name = "true"                 % goal
>> +    ; Name = "fail"                 % goal
>
> Okay.

"or" and "and" are both currently used as predicate / function
names by the bool module.

>> +    ; Name = "with_type"            % goal

I'd be happy to (eventually) remove "with_type" in favour
of ":".

>> +    ; Name = "with_inst"            % goal
>
> I'd rather deprecate these as significant.

What do you mean by that?  (There isn't a replacment
for "with_inst" is there?)

Julien.