### view src/MoreSpecif.v @ 566:1a231194d164

Two new courses
author Adam Chlipala Fri, 19 Oct 2018 10:27:35 -0400 ed829eaa91b2
line wrap: on
line source
```(* Copyright (c) 2008, 2011, 2015, Adam Chlipala
*
* Creative Commons Attribution-Noncommercial-No Derivative Works 3.0
* The license text is available at:
*)

(* Types and notations presented in Chapter 6 *)

Set Implicit Arguments.
Set Asymmetric Patterns.

Notation "!" := (False_rec _ _) : specif_scope.
Notation "[ e ]" := (exist _ e _) : specif_scope.
Notation "x <== e1 ; e2" := (let (x, _) := e1 in e2)
(right associativity, at level 60) : specif_scope.

Local Open Scope specif_scope.
Delimit Scope specif_scope with specif.

Notation "'Yes'" := (left _ _) : specif_scope.
Notation "'No'" := (right _ _) : specif_scope.
Notation "'Reduce' x" := (if x then Yes else No) (at level 50) : specif_scope.

Notation "x || y" := (if x then Yes else Reduce y) (at level 50, left associativity) : specif_scope.

Section sumbool_and.
Variables P1 Q1 P2 Q2 : Prop.

Variable x1 : {P1} + {Q1}.
Variable x2 : {P2} + {Q2}.

Definition sumbool_and : {P1 /\ P2} + {Q1 \/ Q2} :=
match x1 with
| left HP1 =>
match x2 with
| left HP2 => left _ (conj HP1 HP2)
| right HQ2 => right _ (or_intror _ HQ2)
end
| right HQ1 => right _ (or_introl _ HQ1)
end.
End sumbool_and.

Infix "&&" := sumbool_and (at level 40, left associativity) : specif_scope.

Inductive maybe (A : Set) (P : A -> Prop) : Set :=
| Unknown : maybe P
| Found : forall x : A, P x -> maybe P.

Notation "{{ x | P }}" := (maybe (fun x => P)) : specif_scope.
Notation "??" := (Unknown _) : specif_scope.
Notation "[| x |]" := (Found _ x _) : specif_scope.

Notation "x <- e1 ; e2" := (match e1 with
| Unknown => ??
| Found x _ => e2
end)
(right associativity, at level 60) : specif_scope.

Notation "!!" := (inright _ _) : specif_scope.
Notation "[|| x ||]" := (inleft _ [x]) : specif_scope.

Notation "x <-- e1 ; e2" := (match e1 with
| inright _ => !!
| inleft (exist x _) => e2
end)
(right associativity, at level 60) : specif_scope.

Notation "e1 ;; e2" := (if e1 then e2 else ??)
(right associativity, at level 60) : specif_scope.

Notation "e1 ;;; e2" := (if e1 then e2 else !!)
(right associativity, at level 60) : specif_scope.

Section partial.
Variable P : Prop.

Inductive partial : Set :=
| Proved : P -> partial
| Uncertain : partial.
End partial.

Notation "[ P ]" := (partial P) : type_scope.

Notation "'Yes'" := (Proved _) : partial_scope.
Notation "'No'" := (Uncertain _) : partial_scope.

Local Open Scope partial_scope.
Delimit Scope partial_scope with partial.

Notation "'Reduce' v" := (if v then Yes else No) : partial_scope.
Notation "x || y" := (if x then Yes else Reduce y) : partial_scope.
Notation "x && y" := (if x then Reduce y else No) : partial_scope.```