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

[helm.git] / helm / software / lambda-delta / basic_rg / brg.ml

diff --git a/helm/software/lambda-delta/basic_rg/brg.ml b/helm/software/lambda-delta/basic_rg/brg.ml
new file mode 100644 (file)
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+++ b/helm/software/lambda-delta/basic_rg/brg.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_______________________________________________________________ *)
+
+(* kernel version: basic, relative, global *)
+(* note          : ufficial basic lambda-delta *) 
+
+type uri = NUri.uri
+type id = Aut.id
+
+type bind = Void         (* exclusion *)
+          | Abst of term (* abstraction *)
+          | Abbr of term (* abbreviation *)
+
+and term = Sort of attrs * int         (* attrs, hierarchy index *)
+         | LRef of attrs * int         (* attrs, position index *)
+         | GRef of attrs * uri         (* attrs, reference *)
+         | Cast of attrs * term * term (* attrs, type, term *)
+         | Appl of attrs * term * term (* attrs, argument, function *)
+         | Bind of attrs * bind * term (* attrs, binder, scope *)
+
+and attr = Name of bool * id   (* real?, name *)
+         | Entry of int * bind (* age, binder *)
+
+and attrs = attr list
+
+type obj = int * uri * bind (* age, uri, binder, contents *)
+
+type item = obj option
+
+type context = (attrs * bind) list (* attrs, binder *) 
+
+type message = (context, term) Log.item list
+
+(* Currified constructors ***************************************************)
+
+let abst w = Abst w
+
+let abbr v = Abbr v
+
+let lref a i = LRef (a, i)
+
+let cast a u t = Cast (a, u, t)
+
+let appl a u t = Appl (a, u, t)
+
+let bind a b t = Bind (a, b, t)
+
+let bind_abst a u t = Bind (a, Abst u, t)
+
+let bind_abbr a v t = Bind (a, Abbr v, t)
+
+(* context handling functions ***********************************************)
+
+let empty_context = []
+
+let push f es a b =
+   let c = (a, b) :: es in f c
+
+let append f es1 es2 = 
+   f (List.append es2 es1)
+
+let map f map es =
+   Cps.list_map f map es
+
+let contents f es = f es
+
+let get f es i =
+   let rec aux e i = function
+      | []       -> f e None
+      | hd :: tl -> 
+         if i = 0 then f e (Some hd) else 
+        let e = match hd with _, Abst _ -> succ e | _ -> e in  
+        aux e (pred i) tl
+   in
+   aux 0 i es
+
+let rec name f = function
+   | []               -> f None
+   | Name (r, n) :: _ -> f (Some (r, n))
+   | _ :: tl          -> name f tl