author | wenzelm |
Wed, 16 Jan 2002 23:18:20 +0100 | |
changeset 12784 | bab3b002cbbb |
parent 12781 | f76180d14819 |
child 12797 | 4de06a8f67ef |
permissions | -rw-r--r-- |
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(* Title: Pure/pattern.ML |
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ID: $Id$ |
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Author: Tobias Nipkow, Christine Heinzelmann, and Stefan Berghofer |
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License: GPL (GNU GENERAL PUBLIC LICENSE) |
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Unification of Higher-Order Patterns. |
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See also: |
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Tobias Nipkow. Functional Unification of Higher-Order Patterns. |
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In Proceedings of the 8th IEEE Symposium Logic in Computer Science, 1993. |
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Modified pattern.ML to perform proper matching of Higher-Order Patterns.
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Modified pattern.ML to perform proper matching of Higher-Order Patterns.
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TODO: optimize red by special-casing it |
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*) |
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infix aeconv; |
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signature PATTERN = |
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sig |
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type type_sig |
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type sg |
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type env |
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val aeconv : term * term -> bool |
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val eta_contract : term -> term |
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val beta_eta_contract : term -> term |
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val eta_contract_atom : term -> term |
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val match : type_sig -> term * term |
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-> (indexname*typ)list * (indexname*term)list |
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val first_order_match : type_sig -> term * term |
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-> (indexname*typ)list * (indexname*term)list |
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val matches : type_sig -> term * term -> bool |
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val matches_subterm : type_sig -> term * term -> bool |
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val unify : sg * env * (term * term)list -> env |
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val first_order : term -> bool |
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val pattern : term -> bool |
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val rewrite_term : type_sig -> (term * term) list -> term -> term |
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exception Unif |
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exception MATCH |
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exception Pattern |
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end; |
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structure Pattern : PATTERN = |
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struct |
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type type_sig = Type.type_sig |
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type sg = Sign.sg |
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type env = Envir.env |
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exception Unif; |
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exception Pattern; |
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fun occurs(F,t,env) = |
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let fun occ(Var(G,_)) = (case Envir.lookup(env,G) of |
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Some(t) => occ t |
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| None => F=G) |
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| occ(t1$t2) = occ t1 orelse occ t2 |
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| occ(Abs(_,_,t)) = occ t |
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| occ _ = false |
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in occ t end; |
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fun mapbnd f = |
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let fun mpb d (Bound(i)) = if i < d then Bound(i) else Bound(f(i-d)+d) |
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| mpb d (Abs(s,T,t)) = Abs(s,T,mpb(d+1) t) |
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| mpb d ((u1 $ u2)) = (mpb d u1)$(mpb d u2) |
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| mpb _ atom = atom |
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in mpb 0 end; |
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fun idx [] j = ~10000 |
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| idx(i::is) j = if i=j then length is else idx is j; |
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fun at xs i = nth_elem (i,xs); |
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fun mkabs (binders,is,t) = |
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let fun mk(i::is) = let val (x,T) = nth_elem(i,binders) |
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in Abs(x,T,mk is) end |
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| mk [] = t |
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in mk is end; |
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val incr = mapbnd (fn i => i+1); |
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fun ints_of [] = [] |
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| ints_of (Bound i ::bs) = |
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let val is = ints_of bs |
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in if i mem_int is then raise Pattern else i::is end |
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| ints_of _ = raise Pattern; |
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fun ints_of' env ts = ints_of (map (Envir.head_norm env) ts); |
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fun app (s,(i::is)) = app (s$Bound(i),is) |
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| app (s,[]) = s; |
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fun red (Abs(_,_,s)) (i::is) js = red s is (i::js) |
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| red t [] [] = t |
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| red t is jn = app (mapbnd (at jn) t,is); |
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(* split_type ([T1,....,Tn]---> T,n,[]) = ([Tn,...,T1],T) *) |
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fun split_type (T,0,Ts) = (Ts,T) |
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| split_type (Type ("fun",[T1,T2]),n,Ts) = split_type (T2,n-1,T1::Ts) |
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| split_type _ = error("split_type"); |
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fun type_of_G (T,n,is) = |
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let val (Ts,U) = split_type(T,n,[]) in map(at Ts)is ---> U end; |
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fun mkhnf (binders,is,G,js) = mkabs (binders, is, app(G,js)); |
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fun mknewhnf(env,binders,is,F as (a,_),T,js) = |
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let val (env',G) = Envir.genvar a (env,type_of_G(T,length is,js)) |
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in Envir.update((F,mkhnf(binders,is,G,js)),env') end; |
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(* mk_proj_list(is) = [ |is| - k | 1 <= k <= |is| and is[k] >= 0 ] *) |
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fun mk_proj_list is = |
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let fun mk(i::is,j) = if i >= 0 then j :: mk(is,j-1) else mk(is,j-1) |
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| mk([],_) = [] |
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in mk(is,length is - 1) end; |
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fun proj(s,env,binders,is) = |
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let fun trans d i = if i<d then i else (idx is (i-d))+d; |
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fun pr(s,env,d,binders) = (case Envir.head_norm env s of |
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Abs(a,T,t) => let val (t',env') = pr(t,env,d+1,((a,T)::binders)) |
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in (Abs(a,T,t'),env') end |
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| t => (case strip_comb t of |
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(c as Const _,ts) => |
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let val (ts',env') = prs(ts,env,d,binders) |
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in (list_comb(c,ts'),env') end |
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| (f as Free _,ts) => |
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let val (ts',env') = prs(ts,env,d,binders) |
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in (list_comb(f,ts'),env') end |
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| (Bound(i),ts) => |
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let val j = trans d i |
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in if j < 0 then raise Unif |
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else let val (ts',env') = prs(ts,env,d,binders) |
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in (list_comb(Bound j,ts'),env') end |
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end |
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| (Var(F as (a,_),Fty),ts) => |
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let val js = ints_of' env ts; |
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val js' = map (trans d) js; |
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val ks = mk_proj_list js'; |
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val ls = filter (fn i => i >= 0) js' |
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val Hty = type_of_G(Fty,length js,ks) |
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val (env',H) = Envir.genvar a (env,Hty) |
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val env'' = |
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Envir.update((F,mkhnf(binders,js,H,ks)),env') |
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in (app(H,ls),env'') end |
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| _ => raise Pattern)) |
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and prs(s::ss,env,d,binders) = |
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let val (s',env1) = pr(s,env,d,binders) |
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val (ss',env2) = prs(ss,env1,d,binders) |
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in (s'::ss',env2) end |
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| prs([],env,_,_) = ([],env) |
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in if downto0(is,length binders - 1) then (s,env) |
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else pr(s,env,0,binders) |
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end; |
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(* mk_ff_list(is,js) = [ length(is) - k | 1 <= k <= |is| and is[k] = js[k] ] *) |
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fun mk_ff_list(is,js) = |
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let fun mk([],[],_) = [] |
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| mk(i::is,j::js, k) = if i=j then k :: mk(is,js,k-1) |
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else mk(is,js,k-1) |
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parents:
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| mk _ = error"mk_ff_list" |
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in mk(is,js,length is-1) end; |
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fun flexflex1(env,binders,F,Fty,is,js) = |
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if is=js then env |
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else let val ks = mk_ff_list(is,js) |
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in mknewhnf(env,binders,is,F,Fty,ks) end; |
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fun flexflex2(env,binders,F,Fty,is,G,Gty,js) = |
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let fun ff(F,Fty,is,G as (a,_),Gty,js) = |
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if js subset_int is |
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then let val t= mkabs(binders,is,app(Var(G,Gty),map (idx is) js)) |
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in Envir.update((F,t),env) end |
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else let val ks = is inter_int js |
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val Hty = type_of_G(Fty,length is,map (idx is) ks) |
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val (env',H) = Envir.genvar a (env,Hty) |
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fun lam(is) = mkabs(binders,is,app(H,map (idx is) ks)); |
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in Envir.update((G,lam js), Envir.update((F,lam is),env')) |
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end; |
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in if xless(G,F) then ff(F,Fty,is,G,Gty,js) else ff(G,Gty,js,F,Fty,is) end |
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val tsgr = ref(Type.tsig0); |
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fun unify_types(T,U, env as Envir.Envir{asol,iTs,maxidx}) = |
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if T=U then env |
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else let val (iTs',maxidx') = Type.unify (!tsgr) (iTs, maxidx) (U, T) |
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in Envir.Envir{asol=asol,maxidx=maxidx',iTs=iTs'} end |
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handle Type.TUNIFY => raise Unif; |
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fun unif binders (env,(s,t)) = case (Envir.head_norm env s, Envir.head_norm env t) of |
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(Abs(ns,Ts,ts),Abs(nt,Tt,tt)) => |
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let val name = if ns = "" then nt else ns |
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in unif ((name,Ts)::binders) (env,(ts,tt)) end |
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| (Abs(ns,Ts,ts),t) => unif ((ns,Ts)::binders) (env,(ts,(incr t)$Bound(0))) |
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| (t,Abs(nt,Tt,tt)) => unif ((nt,Tt)::binders) (env,((incr t)$Bound(0),tt)) |
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| p => cases(binders,env,p) |
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and cases(binders,env,(s,t)) = case (strip_comb s,strip_comb t) of |
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((Var(F,Fty),ss),(Var(G,Gty),ts)) => |
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if F = G then flexflex1(env,binders,F,Fty,ints_of' env ss,ints_of' env ts) |
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else flexflex2(env,binders,F,Fty,ints_of' env ss,G,Gty,ints_of' env ts) |
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| ((Var(F,_),ss),_) => flexrigid(env,binders,F,ints_of' env ss,t) |
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| (_,(Var(F,_),ts)) => flexrigid(env,binders,F,ints_of' env ts,s) |
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| ((Const c,ss),(Const d,ts)) => rigidrigid(env,binders,c,d,ss,ts) |
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| ((Free(f),ss),(Free(g),ts)) => rigidrigid(env,binders,f,g,ss,ts) |
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| ((Bound(i),ss),(Bound(j),ts)) => rigidrigidB (env,binders,i,j,ss,ts) |
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| ((Abs(_),_),_) => raise Pattern |
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| (_,(Abs(_),_)) => raise Pattern |
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| _ => raise Unif |
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and rigidrigid (env,binders,(a,Ta),(b,Tb),ss,ts) = |
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if a<>b then raise Unif |
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else foldl (unif binders) (unify_types(Ta,Tb,env), ss~~ts) |
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and rigidrigidB (env,binders,i,j,ss,ts) = |
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if i <> j then raise Unif else foldl (unif binders) (env ,ss~~ts) |
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and flexrigid (env,binders,F,is,t) = |
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if occurs(F,t,env) then raise Unif |
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else let val (u,env') = proj(t,env,binders,is) |
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in Envir.update((F,mkabs(binders,is,u)),env') end; |
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fun unify(sg,env,tus) = (tsgr := #tsig(Sign.rep_sg sg); |
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foldl (unif []) (env,tus)); |
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(*Eta-contract a term (fully)*) |
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231 |
(* copying: *) |
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12784 | 232 |
fun eta_contract (Abs(a,T,body)) = |
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(case eta_contract body of |
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body' as (f $ Bound 0) => |
235 |
if loose_bvar1(f,0) then Abs(a,T,body') |
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else incr_boundvars ~1 f |
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| body' => Abs(a,T,body')) |
238 |
| eta_contract(f$t) = eta_contract f $ eta_contract t |
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| eta_contract t = t; |
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240 |
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val beta_eta_contract = eta_contract o Envir.beta_norm; |
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||
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(*Eta-contract a term from outside: just enough to reduce it to an atom |
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244 |
DOESN'T QUITE WORK! |
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245 |
*) |
12784 | 246 |
fun eta_contract_atom (t0 as Abs(a, T, body)) = |
2725
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Declares eta_contract_atom; fixed comment; some tidying
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|
247 |
(case eta_contract2 body of |
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body' as (f $ Bound 0) => |
249 |
if loose_bvar1(f,0) then Abs(a,T,body') |
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250 |
else eta_contract_atom (incr_boundvars ~1 f) |
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Declares eta_contract_atom; fixed comment; some tidying
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| _ => t0) |
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252 |
| eta_contract_atom t = t |
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253 |
and eta_contract2 (f$t) = f $ eta_contract_atom t |
9453616d4b80
Declares eta_contract_atom; fixed comment; some tidying
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|
254 |
| eta_contract2 t = eta_contract_atom t; |
9453616d4b80
Declares eta_contract_atom; fixed comment; some tidying
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255 |
|
9453616d4b80
Declares eta_contract_atom; fixed comment; some tidying
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parents:
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changeset
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256 |
|
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nipkow
parents:
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|
257 |
(*Tests whether 2 terms are alpha/eta-convertible and have same type. |
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changeset
|
258 |
Note that Consts and Vars may have more than one type.*) |
2751 | 259 |
fun t aeconv u = aconv_aux (eta_contract_atom t, eta_contract_atom u) |
260 |
and aconv_aux (Const(a,T), Const(b,U)) = a=b andalso T=U |
|
261 |
| aconv_aux (Free(a,T), Free(b,U)) = a=b andalso T=U |
|
262 |
| aconv_aux (Var(v,T), Var(w,U)) = eq_ix(v,w) andalso T=U |
|
12784 | 263 |
| aconv_aux (Bound i, Bound j) = i=j |
2751 | 264 |
| aconv_aux (Abs(_,T,t), Abs(_,U,u)) = (t aeconv u) andalso T=U |
12784 | 265 |
| aconv_aux (f$t, g$u) = (f aeconv g) andalso (t aeconv u) |
2751 | 266 |
| aconv_aux _ = false; |
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nipkow
parents:
63
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changeset
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|
6151b7f3b606
Modified pattern.ML to perform proper matching of Higher-Order Patterns.
nipkow
parents:
63
diff
changeset
|
268 |
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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|
269 |
(*** Matching ***) |
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270 |
|
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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|
271 |
exception MATCH; |
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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272 |
|
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273 |
fun typ_match tsig args = (Type.typ_match tsig args) |
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274 |
handle Type.TYPE_MATCH => raise MATCH; |
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275 |
|
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276 |
(*First-order matching; |
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277 |
fomatch tsig (pattern, object) returns a (tyvar,typ)list and (var,term)list. |
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278 |
The pattern and object may have variables in common. |
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279 |
Instantiation does not affect the object, so matching ?a with ?a+1 works. |
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280 |
Object is eta-contracted on the fly (by eta-expanding the pattern). |
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281 |
Precondition: the pattern is already eta-contracted! |
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282 |
Note: types are matched on the fly *) |
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283 |
fun fomatch tsig = |
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284 |
let |
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285 |
fun mtch (instsp as (tyinsts,insts)) = fn |
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286 |
(Var(ixn,T), t) => |
12784 | 287 |
if loose_bvar(t,0) then raise MATCH |
288 |
else (case assoc_string_int(insts,ixn) of |
|
289 |
None => (typ_match tsig (tyinsts, (T, fastype_of t)), |
|
290 |
(ixn,t)::insts) |
|
291 |
| Some u => if t aeconv u then instsp else raise MATCH) |
|
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292 |
| (Free (a,T), Free (b,U)) => |
12784 | 293 |
if a=b then (typ_match tsig (tyinsts,(T,U)), insts) else raise MATCH |
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294 |
| (Const (a,T), Const (b,U)) => |
12784 | 295 |
if a=b then (typ_match tsig (tyinsts,(T,U)), insts) else raise MATCH |
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296 |
| (Bound i, Bound j) => if i=j then instsp else raise MATCH |
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297 |
| (Abs(_,T,t), Abs(_,U,u)) => |
12784 | 298 |
mtch (typ_match tsig (tyinsts,(T,U)),insts) (t,u) |
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299 |
| (f$t, g$u) => mtch (mtch instsp (f,g)) (t, u) |
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300 |
| (t, Abs(_,U,u)) => mtch instsp ((incr t)$(Bound 0), u) |
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301 |
| _ => raise MATCH |
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302 |
in mtch end; |
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303 |
|
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|
304 |
fun first_order_match tsig = apfst Vartab.dest o fomatch tsig (Vartab.empty, []); |
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|
305 |
|
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|
306 |
(* Matching of higher-order patterns *) |
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|
307 |
|
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|
308 |
fun match_bind(itms,binders,ixn,is,t) = |
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|
309 |
let val js = loose_bnos t |
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|
310 |
in if null is |
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|
311 |
then if null js then (ixn,t)::itms else raise MATCH |
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312 |
else if js subset_int is |
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|
313 |
then let val t' = if downto0(is,length binders - 1) then t |
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314 |
else mapbnd (idx is) t |
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315 |
in (ixn, mkabs(binders,is,t')) :: itms end |
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|
316 |
else raise MATCH |
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|
317 |
end; |
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|
318 |
|
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|
319 |
fun match tsg (po as (pat,obj)) = |
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|
320 |
let |
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|
321 |
(* Pre: pat and obj have same type *) |
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322 |
fun mtch binders (env as (iTs,itms),(pat,obj)) = |
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|
323 |
case pat of |
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|
324 |
Abs(ns,Ts,ts) => |
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|
325 |
(case obj of |
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|
326 |
Abs(nt,Tt,tt) => mtch ((nt,Tt)::binders) (env,(ts,tt)) |
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|
327 |
| _ => let val Tt = typ_subst_TVars_Vartab iTs Ts |
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|
328 |
in mtch((ns,Tt)::binders)(env,(ts,(incr obj)$Bound(0))) end) |
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|
329 |
| _ => (case obj of |
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|
330 |
Abs(nt,Tt,tt) => |
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|
331 |
mtch((nt,Tt)::binders)(env,((incr pat)$Bound(0),tt)) |
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|
332 |
| _ => cases(binders,env,pat,obj)) |
678
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Modified pattern.ML to perform proper matching of Higher-Order Patterns.
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diff
changeset
|
333 |
|
4820
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|
334 |
and cases(binders,env as (iTs,itms),pat,obj) = |
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|
335 |
let val (ph,pargs) = strip_comb pat |
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|
336 |
fun rigrig1(iTs,oargs) = |
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|
337 |
foldl (mtch binders) ((iTs,itms), pargs~~oargs) |
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|
338 |
fun rigrig2((a,Ta),(b,Tb),oargs) = |
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|
339 |
if a<> b then raise MATCH |
8f6dbbd8d497
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|
340 |
else rigrig1(typ_match tsg (iTs,(Ta,Tb)), oargs) |
8f6dbbd8d497
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|
341 |
in case ph of |
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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|
342 |
Var(ixn,_) => |
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|
343 |
let val is = ints_of pargs |
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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|
344 |
in case assoc_string_int(itms,ixn) of |
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|
345 |
None => (iTs,match_bind(itms,binders,ixn,is,obj)) |
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|
346 |
| Some u => if obj aeconv (red u is []) then env |
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|
347 |
else raise MATCH |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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changeset
|
348 |
end |
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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|
349 |
| _ => |
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|
350 |
let val (oh,oargs) = strip_comb obj |
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|
351 |
in case (ph,oh) of |
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|
352 |
(Const c,Const d) => rigrig2(c,d,oargs) |
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|
353 |
| (Free f,Free g) => rigrig2(f,g,oargs) |
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|
354 |
| (Bound i,Bound j) => if i<>j then raise MATCH |
8f6dbbd8d497
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|
355 |
else rigrig1(iTs,oargs) |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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|
356 |
| (Abs _, _) => raise Pattern |
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|
357 |
| (_, Abs _) => raise Pattern |
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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|
358 |
| _ => raise MATCH |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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|
359 |
end |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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changeset
|
360 |
end; |
678
6151b7f3b606
Modified pattern.ML to perform proper matching of Higher-Order Patterns.
nipkow
parents:
63
diff
changeset
|
361 |
|
4820
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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changeset
|
362 |
val pT = fastype_of pat |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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|
363 |
and oT = fastype_of obj |
8406
a217b0cd304d
Type.unify and Type.typ_match now use Vartab instead of association lists.
berghofe
parents:
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diff
changeset
|
364 |
val iTs = typ_match tsg (Vartab.empty, (pT,oT)) |
4820
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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changeset
|
365 |
val insts2 = (iTs,[]) |
678
6151b7f3b606
Modified pattern.ML to perform proper matching of Higher-Order Patterns.
nipkow
parents:
63
diff
changeset
|
366 |
|
8406
a217b0cd304d
Type.unify and Type.typ_match now use Vartab instead of association lists.
berghofe
parents:
6539
diff
changeset
|
367 |
in apfst Vartab.dest (mtch [] (insts2, po) |
a217b0cd304d
Type.unify and Type.typ_match now use Vartab instead of association lists.
berghofe
parents:
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diff
changeset
|
368 |
handle Pattern => fomatch tsg insts2 po) |
678
6151b7f3b606
Modified pattern.ML to perform proper matching of Higher-Order Patterns.
nipkow
parents:
63
diff
changeset
|
369 |
end; |
0 | 370 |
|
371 |
(*Predicate: does the pattern match the object?*) |
|
678
6151b7f3b606
Modified pattern.ML to perform proper matching of Higher-Order Patterns.
nipkow
parents:
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diff
changeset
|
372 |
fun matches tsig po = (match tsig po; true) handle MATCH => false; |
0 | 373 |
|
4667
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Tried to reorganize rewriter a little. More to be done.
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parents:
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diff
changeset
|
374 |
(* Does pat match a subterm of obj? *) |
6328d427a339
Tried to reorganize rewriter a little. More to be done.
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parents:
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diff
changeset
|
375 |
fun matches_subterm tsig (pat,obj) = |
6328d427a339
Tried to reorganize rewriter a little. More to be done.
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parents:
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changeset
|
376 |
let fun msub(bounds,obj) = matches tsig (pat,obj) orelse |
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Tried to reorganize rewriter a little. More to be done.
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parents:
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changeset
|
377 |
case obj of |
6328d427a339
Tried to reorganize rewriter a little. More to be done.
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parents:
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diff
changeset
|
378 |
Abs(x,T,t) => let val y = variant bounds x |
6328d427a339
Tried to reorganize rewriter a little. More to be done.
nipkow
parents:
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diff
changeset
|
379 |
val f = Free(":" ^ y,T) |
6328d427a339
Tried to reorganize rewriter a little. More to be done.
nipkow
parents:
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diff
changeset
|
380 |
in msub(x::bounds,subst_bound(f,t)) end |
6328d427a339
Tried to reorganize rewriter a little. More to be done.
nipkow
parents:
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diff
changeset
|
381 |
| s$t => msub(bounds,s) orelse msub(bounds,t) |
6328d427a339
Tried to reorganize rewriter a little. More to be done.
nipkow
parents:
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diff
changeset
|
382 |
| _ => false |
6328d427a339
Tried to reorganize rewriter a little. More to be done.
nipkow
parents:
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diff
changeset
|
383 |
in msub([],obj) end; |
6328d427a339
Tried to reorganize rewriter a little. More to be done.
nipkow
parents:
2792
diff
changeset
|
384 |
|
4820
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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diff
changeset
|
385 |
fun first_order(Abs(_,_,t)) = first_order t |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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diff
changeset
|
386 |
| first_order(t $ u) = first_order t andalso first_order u andalso |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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changeset
|
387 |
not(is_Var t) |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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changeset
|
388 |
| first_order _ = true; |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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diff
changeset
|
389 |
|
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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diff
changeset
|
390 |
fun pattern(Abs(_,_,t)) = pattern t |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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diff
changeset
|
391 |
| pattern(t) = let val (head,args) = strip_comb t |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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changeset
|
392 |
in if is_Var head |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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diff
changeset
|
393 |
then let val _ = ints_of args in true end |
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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diff
changeset
|
394 |
handle Pattern => false |
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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diff
changeset
|
395 |
else forall pattern args |
8f6dbbd8d497
Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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diff
changeset
|
396 |
end; |
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Tried to speed up the rewriter by eta-contracting all patterns beforehand and
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parents:
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diff
changeset
|
397 |
|
12784 | 398 |
|
399 |
(* rewriting -- simple but fast *) |
|
400 |
||
401 |
fun rewrite_term tsig rules tm = |
|
402 |
let |
|
403 |
fun match_rew tm (tm1, tm2) = |
|
404 |
Some (subst_vars (match tsig (tm1, tm)) tm2) handle MATCH => None; |
|
405 |
||
406 |
fun rew (Abs (_, _, body) $ t) = Some (subst_bound (t, body)) |
|
407 |
| rew tm = get_first (match_rew tm) rules; |
|
408 |
||
409 |
fun rew0 (tm as Abs (_, _, tm' $ Bound 0)) = |
|
410 |
if loose_bvar1 (tm', 0) then rew tm |
|
411 |
else |
|
412 |
let val tm'' = incr_boundvars ~1 tm' |
|
413 |
in Some (if_none (rew tm'') tm'') end |
|
414 |
| rew0 tm = rew tm; |
|
415 |
||
416 |
fun rew1 tm = (case rew2 tm of |
|
417 |
Some tm1 => (case rew0 tm1 of |
|
418 |
Some tm2 => Some (if_none (rew1 tm2) tm2) |
|
419 |
| None => Some tm1) |
|
420 |
| None => (case rew0 tm of |
|
421 |
Some tm1 => Some (if_none (rew1 tm1) tm1) |
|
422 |
| None => None)) |
|
423 |
||
424 |
and rew2 (tm1 $ tm2) = (case tm1 of |
|
425 |
Abs (_, _, body) => |
|
426 |
let val tm' = subst_bound (tm2, body) |
|
427 |
in Some (if_none (rew2 tm') tm') end |
|
428 |
| _ => (case rew1 tm1 of |
|
429 |
Some tm1' => (case rew1 tm2 of |
|
430 |
Some tm2' => Some (tm1' $ tm2') |
|
431 |
| None => Some (tm1' $ tm2)) |
|
432 |
| None => (case rew1 tm2 of |
|
433 |
Some tm2' => Some (tm1 $ tm2') |
|
434 |
| None => None))) |
|
435 |
| rew2 (Abs (x, T, tm)) = (case rew1 tm of |
|
436 |
Some tm' => Some (Abs (x, T, tm')) |
|
437 |
| None => None) |
|
438 |
| rew2 _ = None |
|
439 |
||
440 |
in if_none (rew1 tm) tm end; |
|
441 |
||
0 | 442 |
end; |