removed True_implies (cf. True_implies_equals);
(* Title: HOL/Tools/function_package/fundef_package.ML
ID: $Id$
Author: Alexander Krauss, TU Muenchen
A package for general recursive function definitions.
Automatic splitting of overlapping constructor patterns. This is a preprocessing step which
turns a specification with overlaps into an overlap-free specification.
*)
signature FUNDEF_SPLIT =
sig
val split_some_equations :
Proof.context -> (('a * ('b * bool)) * term) list -> (('a * 'b) * term list) list
end
structure FundefSplit : FUNDEF_SPLIT =
struct
(* We use proof context for the variable management *)
(* FIXME: no __ *)
fun new_var ctx vs T =
let
val [v] = Variable.variant_frees ctx vs [("v", T)]
in
(Free v :: vs, Free v)
end
fun saturate ctx vs t =
fold (fn T => fn (vs, t) => new_var ctx vs T |> apsnd (curry op $ t))
(binder_types (fastype_of t)) (vs, t)
(* This is copied from "fundef_datatype.ML" *)
fun inst_constrs_of thy (T as Type (name, _)) =
map (fn (Cn,CT) => Envir.subst_TVars (Type.typ_match (Sign.tsig_of thy) (body_type CT, T) Vartab.empty) (Const (Cn, CT)))
(the (DatatypePackage.get_datatype_constrs thy name))
| inst_constrs_of thy t = (print t; sys_error "inst_constrs_of")
fun pattern_subtract_subst ctx vs _ (Free v2) = []
| pattern_subtract_subst ctx vs (v as (Free (_, T))) t' =
let
fun foo constr =
let
val (vs', t) = saturate ctx vs constr
val substs = pattern_subtract_subst ctx vs' t t'
in
map (cons (v, t)) substs
end
in
flat (map foo (inst_constrs_of (ProofContext.theory_of ctx) T))
end
| pattern_subtract_subst ctx vs t t' =
let
val (C, ps) = strip_comb t
val (C', qs) = strip_comb t'
in
if C = C'
then flat (map2 (pattern_subtract_subst ctx vs) ps qs)
else [[]]
end
fun pattern_subtract_parallel ctx vs ps qs =
flat (map2 (pattern_subtract_subst ctx vs) ps qs)
(* ps - qs *)
fun pattern_subtract ctx eq2 eq1 =
let
val _ $ (_ $ lhs1 $ _) = eq1
val _ $ (_ $ lhs2 $ _) = eq2
val thy = ProofContext.theory_of ctx
val vs = term_frees eq1
in
map (fn sigma => Pattern.rewrite_term thy sigma [] eq1) (pattern_subtract_subst ctx vs lhs1 lhs2)
end
(* ps - p' *)
fun pattern_subtract_from_many ctx p'=
flat o map (pattern_subtract ctx p')
(* in reverse order *)
fun pattern_subtract_many ctx ps' =
fold_rev (pattern_subtract_from_many ctx) ps'
fun split_all_equations ctx eqns =
let
fun split_aux prev [] = []
| split_aux prev (e::es) = pattern_subtract_many ctx prev [e] @ split_aux (e::prev) es
in
split_aux [] eqns
end
fun split_some_equations ctx eqns =
let
fun split_aux prevs [] = []
| split_aux prev (((n, (att, true)), eq) :: es) = ((n, att), pattern_subtract_many ctx prev [eq])
:: split_aux (eq :: prev) es
| split_aux prev (((n, (att, false)), eq) :: es) = ((n, att), [eq])
:: split_aux (eq :: prev) es
in
split_aux [] eqns
end
end