new kernel basic_rg: implements ufficial lambda-delta with de Bruijn indexes

[helm.git] / helm / software / lambda-delta / toplevel / metaBrg.ml

diff --git a/helm/software/lambda-delta/toplevel/metaBrg.ml b/helm/software/lambda-delta/toplevel/metaBrg.ml
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+(*
+    ||M||  This file is part of HELM, an Hypertextual, Electronic        
+    ||A||  Library of Mathematics, developed at the Computer Science     
+    ||T||  Department, University of Bologna, Italy.                     
+    ||I||                                                                
+    ||T||  HELM is free software; you can redistribute it and/or         
+    ||A||  modify it under the terms of the GNU General Public License   
+    \   /  version 2 or (at your option) any later version.              
+     \ /   This software is distributed as is, NO WARRANTY.              
+      V_______________________________________________________________ *)
+
+module C = Cps
+module B = Brg
+module M = Meta
+
+(* Internal functions *******************************************************)
+
+let rec xlate_term c f = function
+   | M.Sort s            -> 
+      let f h = f (B.Sort ([], h)) in
+      if s then f 0 else f 1
+   | M.LRef (_, i)       ->
+      f (B.LRef ([], i))
+   | M.GRef (_, uri, vs) ->
+      let map f t v = f (B.appl [] v t) in
+      let f vs = C.list_fold_left f map (B.GRef ([], uri)) vs in
+      C.list_map f (xlate_term c) vs
+   | M.Appl (v, t)       ->
+      let f v t = f (B.Appl ([], v, t)) in
+      let f v = xlate_term c (f v) t in
+      xlate_term c f v
+   | M.Abst (id, w, t)   ->
+      let f w = 
+         let a = [B.Name (true, id)] in
+        let f t = f (B.Bind (a, B.Abst w, t)) in
+         let f c = xlate_term c f t in
+         B.push f c a (B.Abst w)
+      in
+      xlate_term c f w
+
+let xlate_pars f pars =
+   let map f (id, w) c =
+      let a = [B.Name (true, id)] in
+      let f w = B.push f c a (B.Abst w) in
+      xlate_term c f w
+   in
+   C.list_fold_right f map pars B.empty_context
+
+let unwind_to_xlate_term f c t =
+   let map f t (a, b) = f (B.bind a b t) in
+   let f t = C.list_fold_left f map t c in
+   xlate_term c f t
+
+let xlate_entry f = function
+   | e, pars, uri, u, None        ->
+      let f u = f (e, uri, B.Abst u) in
+      let f c = unwind_to_xlate_term f c u in      
+      xlate_pars f pars   
+   | e, pars, uri, u, Some (_, t) ->
+      let f u t = f (e, uri, B.Abbr (B.Cast ([], u, t))) in
+      let f c u = unwind_to_xlate_term (f u) c t in
+      let f c = unwind_to_xlate_term (f c) c u in
+      xlate_pars f pars
+
+let xlate_item f = function
+   | None   -> f None
+   | Some e -> let f e = f (Some e) in xlate_entry f e
+
+(* Interface functions ******************************************************)
+
+let brg_of_meta = xlate_item