Type Inference for an Interpretive Language

csw@public.btr.com (Charles S. Wetherell csw@btr.com)
Fri, 12 Mar 1993 18:03:36 GMT

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Type Inference for an Interpretive Language csw@public.btr.com (1993-03-12)
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Newsgroups: comp.compilers
From: csw@public.btr.com (Charles S. Wetherell csw@btr.com)
Keywords: types, analysis, question
Organization: BTR UNIX BBS
Date: Fri, 12 Mar 1993 18:03:36 GMT


I am writing a compiler for a language which is currently interpretive.
The goal is to create objects which are much faster (order of magnitude,
at least) than the interpretive versions. The language does not require
(indeed, has no mechanism for), variable declarations; the type and size
of storage for every variable and formal parameter is determined at each
use. Therefore, an assignment like

      A = B + C

can change the type and the storage for A depending on B and C; the
operation "+" may have different (though predefined) effects depending on
the types and sizes of B and C). The languge is otherwise a
straightforward imperative, procedural language not so different from
Basic, say.

Therefore, I am interested in algorithms to infer the types of variables
and to fix the types of polymorphic operators. I am familiar with some of
the work of Meertens on B, Mitchell on inference and coercion, several
works on Smalltalk inference and on ML inference, of Fagan and Cartwright
on soft typing, and of Chambers and Ungar on SELF. There is a brief note
in Aho, Sethi, and Ullman (Red Dragon) that the general problem of type
inference for variables in languages with function polymorphism is
undecidable; they suggest that this is a result coming from the work with
HOPE. I have not been able to track that result down.

I would appreciate any comments or pointers the readers of this group
might be able to give to

      further theoretical work on type inference

      type inference in the presence of traditional flow

      interprocedural type inference

      type inference in practical languages

      translations systems which use type inference

Please mail your comments to me; if there is enough to warrant, I will
summarize and post to the net.

Thank you in advance for your help

Charles Wetherell

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