(* ========================================================================== *) (* FLYSPECK - BOOK FORMALIZATION *) (* *) (* Chapter: Jordan *) (* Copied from HOL Light jordan directory *) (* Author: Thomas C. Hales *) (* Date: 2010-07-08 *) (* ========================================================================== *) module Hash_term = struct let hash_of_string = let prime200 = 1223 in let prime = 8831 in let rec hashll v = match v with | [] -> 0 | h::t -> (int_of_char (String.get h 0) + prime200*( hashll t)) mod prime in fun s -> let slt = explode s in hashll slt;; let saved_hashstring = ref ((Hashtbl.create 300):(string,int) Hashtbl.t);; let save_hashstring string = Hashtbl.add !saved_hashstring (string) (hash_of_string string);; let mem_hashstring s = Hashtbl.mem !saved_hashstring s;; let remove_hashstring s = Hashtbl.remove !saved_hashstring s;; let find_hashstring s = Hashtbl.find !saved_hashstring s;; let memhash_of_string s = if not(mem_hashstring s) then (save_hashstring s) ; find_hashstring s;; let hash_of_type = let prime150 = 863 in let prime160 = 941 in let prime180 = 1069 in let prime190 = 1151 in let prime1200 = 9733 in let rec hashl u = match u with | [] -> 0 | h::t -> ((hasht h) + prime190*(hashl t)) mod prime1200 and hasht v = match v with | Tyvar s -> (prime150*memhash_of_string s + prime160) mod prime1200 | Tyapp (s,tlt) -> let h = memhash_of_string s in let h2 = (h*h) mod prime1200 in (prime180*h2 + hashl tlt ) mod prime1200 in hasht;; (* make hash_of_term constant on alpha-equivalence classes of terms *) let rename_var n = fun v -> mk_var ("??_"^(string_of_int n),type_of v);; let paform = let rec raform n env tm = match tm with | Var(_,_) -> assocd tm env tm | Const(_,_) -> tm | Comb (s,t) -> mk_comb(raform n env s, raform n env t) | Abs (x,t) -> let x1 = rename_var n x in mk_abs(x1, raform (n+1) ((x,x1)::env) t) in raform 0 [];; let hash_of_term = let prime1220 = 9887 in let prime210 = 1291 in let prime220 = 1373 in let prime230 = 1451 in let prime240 = 1511 in let prime250 = 1583 in let prime260 = 1657 in let prime270 = 1733 in let prime280 = 1811 in let rec hasht u = match u with | Var (s,t) -> (prime210*(memhash_of_string s) + hash_of_type t) mod prime1220 | Const (s,t) -> (prime220*(memhash_of_string s) + hash_of_type t) mod prime1220 | Comb (s,t) -> let h = hasht s in let h2 = (h*h) mod prime1220 in (prime230*h2 + prime240*hasht t + prime250) mod prime1220 | Abs (s,t) -> let h = hasht s in let h2 = (h*h) mod prime1220 in (prime260*h2 + prime270*hasht t + prime280) mod prime1220 in hasht o paform;; end;;