Arith: full integration of the "Numbers" modular framework

 - The earlier proof-of-concept file NPeano (which instantiates
   the "Numbers" framework for nat) becomes now the entry point
   in the Arith lib, and gets renamed PeanoNat. It still provides
   an inner module "Nat" which sums up everything about type nat
   (functions, predicates and properties of them).
   This inner module Nat is usable as soon as you Require Import Arith,
   or just Arith_base, or simply PeanoNat.

 - Definitions of operations over type nat are now grouped in a new
   file Init/Nat.v. This file is meant to be used without "Import",
   hence providing for instance Nat.add or Nat.sqrt as soon as coqtop
   starts (but no proofs about them).

 - The definitions that used to be in Init/Peano.v (pred, plus, minus, mult)
   are now compatibility notations (for Nat.pred, Nat.add, Nat.sub, Nat.mul
   where here Nat is Init/Nat.v).

 - This Coq.Init.Nat module (with only pure definitions) is Include'd
   in the aforementioned Coq.Arith.PeanoNat.Nat. You might see Init.Nat
   sometimes instead of just Nat (for instance when doing "Print plus").
   Normally it should be ok to just ignore these "Init" since
   Init.Nat is included in the full PeanoNat.Nat. I'm investigating if
   it's possible to get rid of these "Init" prefixes.

 - Concerning predicates, orders le and lt are still defined in Init/Peano.v,
   with their notations "<=" and "<". Properties in PeanoNat.Nat directly
   refer to these predicates in Peano. For instantation reasons, PeanoNat.Nat
   also contains a Nat.le and Nat.lt (defined via "Definition le := Peano.le",
   we cannot yet include an Inductive to implement a Parameter), but these
   aliased predicates won't probably be very convenient to use.

 - Technical remark: I've split the previous property functor NProp in
   two parts (NBasicProp and NExtraProp), it helps a lot for building
   PeanoNat.Nat incrementally. Roughly speaking, we have the following schema:

   Module Nat.
     Include Coq.Init.Nat. (* definition of operations : add ... sqrt ... *)
     ... (** proofs of specifications for basic ops such as + * - *)
     Include NBasicProp. (** generic properties of these basic ops *)
     ... (** proofs of specifications for advanced ops (pow sqrt log2...)
             that may rely on proofs for + * - *)
     Include NExtraProp. (** all remaining properties *)
   End Nat.

- All other files in directory Arith are now taking advantage of PeanoNat :
  they are now filled with compatibility notations (when earlier lemmas
  have exact counterpart in the Nat module) or lemmas with one-line proofs
  based on the Nat module. All hints for database "arith" remain declared
  in these old-style file (such as Plus.v, Lt.v, etc). All the old-style
  files are still Require'd (or not) by Arith.v, just as before.

- Compatibility should be almost complete. For instance in the stdlib,
  the only adaptations were due to .ml code referring to some Coq constant
  name such as Coq.Init.Peano.pred, which doesn't live well with the
  new compatibility notations.

1 files changed, 52 insertions, 47 deletions

diff --git a/theories/NArith/Ndigits.v b/theories/NArith/Ndigits.v
index 662c50abf..b36ea3204 100644
--- a/theories/NArith/Ndigits.v
+++ b/theories/NArith/Ndigits.v
@@ -6,8 +6,7 @@
 (*         *       GNU Lesser General Public License Version 2.1        *)
 (************************************************************************)
 
-Require Import Bool Morphisms Setoid Bvector BinPos BinNat Wf_nat
- Pnat Nnat Compare_dec Lt Minus.
+Require Import Bool Morphisms Setoid Bvector BinPos BinNat PeanoNat Pnat Nnat.
 
 Local Open Scope N_scope.
 
@@ -111,10 +110,12 @@ Lemma Nshiftl_nat_spec_high : forall a n m, (n<=m)%nat ->
   N.testbit_nat (N.shiftl_nat a n) m = N.testbit_nat a (m-n).
 Proof.
  induction n; intros m H.
- now rewrite <- minus_n_O.
- destruct m. inversion H. apply le_S_n in H.
- simpl. rewrite <- IHn; trivial.
- destruct (N.shiftl_nat a n) as [|[p|p|]]; simpl; trivial.
+ - now rewrite Nat.sub_0_r.
+ - destruct m.
+   + inversion H.
+   + apply le_S_n in H.
+     simpl. rewrite <- IHn; trivial.
+     destruct (N.shiftl_nat a n) as [|[p|p|]]; simpl; trivial.
 Qed.
 
 Lemma Nshiftl_nat_spec_low : forall a n m, (m<n)%nat ->
@@ -123,9 +124,10 @@ Proof.
  induction n; intros m H. inversion H.
  rewrite Nshiftl_nat_S.
  destruct m.
- destruct (N.shiftl_nat a n); trivial.
- specialize (IHn m (lt_S_n _ _ H)).
- destruct (N.shiftl_nat a n); trivial.
+ - destruct (N.shiftl_nat a n); trivial.
+ - apply Lt.lt_S_n in H.
+   specialize (IHn m H).
+   destruct (N.shiftl_nat a n); trivial.
 Qed.
 
 (** A left shift for positive numbers (used in BigN) *)
@@ -446,49 +448,52 @@ Lemma Nless_trans :
    Nless a a' = true -> Nless a' a'' = true -> Nless a a'' = true.
 Proof.
   induction a as [|a IHa|a IHa] using N.binary_ind; intros a' a'' H H0.
-    case_eq (Nless N0 a'') ; intros Heqn. trivial.
-     rewrite (N0_less_2 a'' Heqn), (Nless_z a') in H0. discriminate H0.
-    induction a' as [|a' _|a' _] using N.binary_ind.
-      rewrite (Nless_z (N.double a)) in H. discriminate H.
-      rewrite (Nless_def_1 a a') in H.
-       induction a'' using N.binary_ind.
-         rewrite (Nless_z (N.double a')) in H0. discriminate H0.
-         rewrite (Nless_def_1 a' a'') in H0. rewrite (Nless_def_1 a a'').
-          exact (IHa _ _ H H0).
-         apply Nless_def_3.
-      induction a'' as [|a'' _|a'' _] using N.binary_ind.
-        rewrite (Nless_z (N.succ_double a')) in H0. discriminate H0.
-        rewrite (Nless_def_4 a' a'') in H0. discriminate H0.
-        apply Nless_def_3.
-    induction a' as [|a' _|a' _] using N.binary_ind.
-      rewrite (Nless_z (N.succ_double a)) in H. discriminate H.
-      rewrite (Nless_def_4 a a') in H. discriminate H.
+  - case_eq (Nless N0 a'') ; intros Heqn.
+    + trivial.
+    + rewrite (N0_less_2 a'' Heqn), (Nless_z a') in H0. discriminate H0.
+  - induction a' as [|a' _|a' _] using N.binary_ind.
+    + rewrite (Nless_z (N.double a)) in H. discriminate H.
+    + rewrite (Nless_def_1 a a') in H.
       induction a'' using N.binary_ind.
-        rewrite (Nless_z (N.succ_double a')) in H0. discriminate H0.
-        rewrite (Nless_def_4 a' a'') in H0. discriminate H0.
-        rewrite (Nless_def_2 a' a'') in H0. rewrite (Nless_def_2 a a') in H.
-          rewrite (Nless_def_2 a a''). exact (IHa _ _ H H0).
+      * rewrite (Nless_z (N.double a')) in H0. discriminate H0.
+      * rewrite (Nless_def_1 a' a'') in H0. rewrite (Nless_def_1 a a'').
+        exact (IHa _ _ H H0).
+      * apply Nless_def_3.
+    + induction a'' as [|a'' _|a'' _] using N.binary_ind.
+      * rewrite (Nless_z (N.succ_double a')) in H0. discriminate H0.
+      * rewrite (Nless_def_4 a' a'') in H0. discriminate H0.
+      * apply Nless_def_3.
+  - induction a' as [|a' _|a' _] using N.binary_ind.
+    + rewrite (Nless_z (N.succ_double a)) in H. discriminate H.
+    + rewrite (Nless_def_4 a a') in H. discriminate H.
+    + induction a'' using N.binary_ind.
+      * rewrite (Nless_z (N.succ_double a')) in H0. discriminate H0.
+      * rewrite (Nless_def_4 a' a'') in H0. discriminate H0.
+      * rewrite (Nless_def_2 a' a'') in H0. rewrite (Nless_def_2 a a') in H.
+        rewrite (Nless_def_2 a a''). exact (IHa _ _ H H0).
 Qed.
 
 Lemma Nless_total :
  forall a a', {Nless a a' = true} + {Nless a' a = true} + {a = a'}.
 Proof.
   induction a using N.binary_rec; intro a'.
-    case_eq (Nless N0 a') ; intros Heqb. left. left. auto.
-     right. rewrite (N0_less_2 a' Heqb). reflexivity.
-    induction a' as [|a' _|a' _] using N.binary_rec.
-      case_eq (Nless N0 (N.double a)) ; intros Heqb. left. right. auto.
-       right. exact (N0_less_2 _  Heqb).
-      rewrite 2!Nless_def_1. destruct (IHa a') as [ | ->].
-        left. assumption.
-        right. reflexivity.
-    left. left. apply Nless_def_3.
-    induction a' as [|a' _|a' _] using N.binary_rec.
-      left. right. destruct a; reflexivity.
-      left. right. apply Nless_def_3.
-      rewrite 2!Nless_def_2. destruct (IHa a') as [ | ->].
-        left. assumption.
-        right. reflexivity.
+  - case_eq (Nless N0 a') ; intros Heqb.
+    + left. left. auto.
+    + right. rewrite (N0_less_2 a' Heqb). reflexivity.
+  - induction a' as [|a' _|a' _] using N.binary_rec.
+    + case_eq (Nless N0 (N.double a)) ; intros Heqb.
+      * left. right. auto.
+      * right. exact (N0_less_2 _  Heqb).
+    + rewrite 2!Nless_def_1. destruct (IHa a') as [ | ->].
+      * left. assumption.
+      * right. reflexivity.
+    + left. left. apply Nless_def_3.
+  - induction a' as [|a' _|a' _] using N.binary_rec.
+    + left. right. destruct a; reflexivity.
+    + left. right. apply Nless_def_3.
+    + rewrite 2!Nless_def_2. destruct (IHa a') as [ | ->].
+      * left. assumption.
+      * right. reflexivity.
 Qed.
 
 (** Number of digits in a number *)
@@ -622,7 +627,7 @@ induction bv; intros.
 inversion H.
 destruct p ; simpl.
   destruct (Bv2N n bv); destruct h; simpl in *; auto.
-  specialize IHbv with p (lt_S_n _ _ H).
+  specialize IHbv with p (Lt.lt_S_n _ _ H).
     simpl in * ; destruct (Bv2N n bv); destruct h; simpl in *; auto.
 Qed.
 
@@ -641,7 +646,7 @@ Proof.
 destruct n as [|n].
 inversion H.
 induction n ; destruct p ; unfold Vector.nth_order in *; simpl in * ; auto.
-intros H ; destruct (lt_n_O _ (lt_S_n _ _ H)).
+intros H ; destruct (Lt.lt_n_O _ (Lt.lt_S_n _ _ H)).
 Qed.
 
 (** Binary bitwise operations are the same in the two worlds. *)