Commit 3cb126ca authored by Robbert Krebbers's avatar Robbert Krebbers

More documentation for the type class logical operators.

parent 878aa716
Pipeline #4369 passed with stage
in 12 minutes and 17 seconds
......@@ -25,9 +25,22 @@ Arguments unseal {_ _} _.
Arguments seal_eq {_ _} _.
Unset Primitive Projections.
(* The [Or] class is useful for efficiency: instead of having two instances
[P → Q1 → R] and [P → Q2 → R] we could have one instance [P → Or Q1 Q2 → R],
which avoids the need to derive [P] twice. *)
(* Below we define type class versions of the common logical operators. It is
important to note that we duplicate the definitions, and do not declare the
existing logical operators as type classes. That is, we do not say:
Existing Class or.
Existing Class and.
If we could define the existing logical operators as classes, there is no way
of disambiguating whether a premise of a lemma should be solved by type class
resolution or not.
These classes are useful for two purposes: writing complicated type class
premises in a more concise way, and for efficiency. For example, using the [Or]
class, instead of defining two instances [P → Q1 → R] and [P → Q2 → R] we could
have one instance [P → Or Q1 Q2 → R]. When we declare the instance that way, we
avoid the need to derive [P] twice. *)
Inductive TCOr (P1 P2 : Prop) : Prop :=
| TCOr_l : P1 TCOr P1 P2
| TCOr_r : P2 TCOr P1 P2.
......
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