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Re: Common Lisp solved this problem 20 years ago



Aubrey Jaffer wrote:
Are you suggesting that we have syntax specific to the SRFI-77
categories; or a general type declaration system?

If type inference is a general problem, why not provide a general solution?

Or, if a general type mechanism is too radical, why not use a subset to solve the particular problem for arithmetic in R6RS and leave the rest to R7RS. If you have forms that declare certain named variables are fixnums/flonums and that certain expressions yield fixnums/flonums, you are most of the way there. These can probably be provided in a way that can be transparently extended to real types.

Specific sounds good to me.  Can you propose a specific set of
syntaxes?

There are examples of type declarations in Common Lisp, Dylan, Kawa, Bigloo, and I am sure other lisps. Let's look at them before we try to invent something new.

Per, would you summarize the syntax and semantics of type declarations in Kawa, please?

Regards,

Alan
--
Dr Alan Watson
Centro de Radioastronomía y Astrofísica
Universidad Astronómico Nacional de México