Stuff moved from old Matita.

[helm.git] / matita / matita / contribs / ng_assembly2 / common / option_base.ma

diff --git a/matita/matita/contribs/ng_assembly2/common/option_base.ma b/matita/matita/contribs/ng_assembly2/common/option_base.ma
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+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||M||                                                             *)
+(*      ||A||       A project by Andrea Asperti                           *)
+(*      ||T||                                                             *)
+(*      ||I||       Developers:                                           *)
+(*      ||T||         The HELM team.                                      *)
+(*      ||A||         http://helm.cs.unibo.it                             *)
+(*      \   /                                                             *)
+(*       \ /        This file is distributed under the terms of the       *)
+(*        v         GNU General Public License Version 2                  *)
+(*                                                                        *)
+(**************************************************************************)
+
+(* ********************************************************************** *)
+(*                          Progetto FreeScale                            *)
+(*                                                                        *)
+(*   Sviluppato da: Ing. Cosimo Oliboni, oliboni@cs.unibo.it              *)
+(*   Sviluppo: 2008-2010                                                  *)
+(*                                                                        *)
+(* ********************************************************************** *)
+
+include "num/bool.ma".
+
+(* ****** *)
+(* OPTION *)
+(* ****** *)
+
+ninductive option (A:Type) : Type ≝
+  None : option A
+| Some : A → option A.
+
+ndefinition eq_option ≝
+λT.λf:T → T → bool.λop1,op2:option T.
+ match op1 with
+  [ None ⇒ match op2 with [ None ⇒ true | Some _ ⇒ false ]
+  | Some x1 ⇒ match op2 with [ None ⇒ false | Some x2 ⇒ f x1 x2 ]
+  ].
+
+(* option map = match ... with [ None ⇒ None ? | Some .. ⇒ .. ] *)
+ndefinition opt_map ≝
+λT1,T2:Type.λt:option T1.λf:T1 → option T2.
+ match t with [ None ⇒ None ? | Some x ⇒ (f x) ].