Re: Calling inherited primitive operations in Ada

[Emmanuel Briot <briot.emmanuel@gmail.com>]

> not user friendly. There appears to be extensive HTML documentation, but it can 
> only be viewed as HTML source in Github, which is not easy to read, so I didn't. 

Those are generated from the .rst files in docs_src/

> typical user, for whom using a hashed-map abstraction should be as simple as 
> 
> function Hash (Key : in Identifier) return Hash_Value; 
> package Maps is new Lib.Maps 
> (Identifier => Identifier, Associated_Value => Associated_Value); 

Maps are created as

   package Maps0 is new GAL.Maps.Def_Def_Unbounded
      (Integer,
       Element_Type => Integer,
       Hash => Test_Support.Hash,
       Container_Base_Type => GAL.Controlled_Base);

The only addition here is `Container_Base_Type`, and that's because the library is probable with SPARK, and the latter doesn't support controlled types.
And Ada doesn't support default values for the formal parameters of generics (another annoying limitation !)

> I was not willing to spend more than about 15 minutes trying to understand this, 
> so I may be missing something.

Fair enough. The library is really a set of experiments, mostly successful, and I think it might have been used for the implementation of the current
SPARK containers in GNAT, though I am not positive there.
I did look at the pragmARC components, and there you indeed chose to have a large number of similar-looking packages and code duplication. I guess
we'll have just to agree to disagree on the design approach there. But of course, users having choices is what makes an ecosystem interesting.

What I was really going after are graphs and their algorithms. In particular, I want those algorithms to work on any graph data structure provided it has
a number of primitive operations. In fact, the algorithm could also work when the graph is kind of implicit in the code, even if we do not have an actual
Graph object. And those this, you need generics.

A similar approach is what Rust uses all over the place with its traits, or what C++ Boost library uses for its graphs, too.