The new Internal Interface for Theory Extension
===============================================
MMW 06-Jun-1994
In former versions of Isabelle, the interface for theory extension was
provided by extend_theory. This had many deficiencies and has been removed in
Isabelle94/2.
Instead of one monolithic function, there is now a host of small functions of
the form:
add_XXX: ... -> theory -> theory
These provide an extension mechanism which is:
- incremental (but non-destructive):
An extend operation may now involve many functions of the add_XXX kind.
These act in a purely functional manner.
- nameless:
One no longer needs to invent new theory names for intermediate theories.
There's now a notion of _draft_theories_ that behave like ordinary ones
in many cases (main exceptions: extensions of drafts are not related (wrt
subthy); merges of drafts with unrelated theories are impossible). A
draft is "closed" by add_thyname.
- extendable:
Package writers simply have to provide add_XXX like functions, which are
built using a basic set provided by Pure Isabelle.
Here follows a sample interactive session using the new functions:
> add_consts
# [("nand", "[o, o] => o", NoSyn), ("#", "[o, o] => o", Infixl 30)]
# FOL.thy;
Building new grammar...
val it = {Pure, IFOL, FOL, #} : theory
> add_axioms
# [("nand_def", "nand(P, Q) == ~(P & Q)"), ("xor_def", "P # Q == P & ~Q | ~P & Q")]
# it;
val it = {Pure, IFOL, FOL, #} : theory
> add_thyname "Gate" it;
val it = {Pure, IFOL, FOL, Gate} : theory
Note that theories and theorems with a "#" draft stamp are not supposed to
persist. Typically, there is a final add_thyname somewhere with the "real"
theory name as supplied by the user.
Appendix A: Basic theory extension functions
--------------------------------------------
val add_classes: (class list * class * class list) list -> theory -> theory
val add_defsort: sort -> theory -> theory
val add_types: (string * int * mixfix) list -> theory -> theory
val add_tyabbrs: (string * string list * string * mixfix) list
-> theory -> theory
val add_tyabbrs_i: (string * string list * typ * mixfix) list
-> theory -> theory
val add_arities: (string * sort list * sort) list -> theory -> theory
val add_consts: (string * string * mixfix) list -> theory -> theory
val add_consts_i: (string * typ * mixfix) list -> theory -> theory
val add_syntax: (string * string * mixfix) list -> theory -> theory
val add_syntax_i: (string * typ * mixfix) list -> theory -> theory
val add_trfuns:
(string * (ast list -> ast)) list *
(string * (term list -> term)) list *
(string * (term list -> term)) list *
(string * (ast list -> ast)) list -> theory -> theory
val add_trrules: xrule list -> theory -> theory
val add_axioms: (string * string) list -> theory -> theory
val add_axioms_i: (string * term) list -> theory -> theory
val add_thyname: string -> theory -> theory
Appendix B: The |> operator
---------------------------
Isabelle now provides an ML infix operator for reverse function application:
infix |>;
fun (x |> f) = f x;
Using this, theory extension really becomes a pleasure, e.g.:
FOL.thy
|> add_consts
[("nand", "[o, o] => o", NoSyn),
("#", "[o, o] => o", Infixl 30)]
|> add_axioms
[("nand_def", "nand(P, Q) == ~(P & Q)"),
("xor_def", "P # Q == P & ~Q | ~P & Q")]
|> add_thyname "Gate";
For a real-world example simply reset delete_tmpfiles, use_thy your favourite
theory definition file and inspect the generated .XXX.thy.ML file.
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