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David Swasey
coqstdpp
Commits
d8445c86
Commit
d8445c86
authored
Jan 05, 2013
by
Robbert Krebbers
Browse files
Add a type class to collect types that are inhabited.
parent
507a150a
Changes
2
Hide whitespace changes
Inline
Sidebyside
theories/base.v
View file @
d8445c86
...
...
@@ 86,6 +86,28 @@ on a type [A] we write [`{∀ x y : A, Decision (x = y)}] and use it by writing
Class
Decision
(
P
:
Prop
)
:
=
decide
:
{
P
}
+
{
¬
P
}.
Arguments
decide
_
{
_
}.
(** ** Inhabited types *)
(** This type class collects types that are inhabited. *)
Class
Inhabited
(
A
:
Type
)
:
Prop
:
=
populate
{
_
:
A
}.
Arguments
populate
{
_
}
_
.
Instance
unit_inhabited
:
Inhabited
unit
:
=
populate
().
Instance
list_inhabited
{
A
}
:
Inhabited
(
list
A
)
:
=
populate
[].
Instance
prod_inhabited
{
A
B
}
(
iA
:
Inhabited
A
)
(
iB
:
Inhabited
B
)
:
Inhabited
(
A
*
B
)
:
=
match
iA
,
iB
with

populate
x
,
populate
y
=>
populate
(
x
,
y
)
end
.
Instance
sum_inhabited_l
{
A
B
}
(
iA
:
Inhabited
A
)
:
Inhabited
(
A
+
B
)
:
=
match
iA
with

populate
x
=>
populate
(
inl
x
)
end
.
Instance
sum_inhabited_r
{
A
B
}
(
iB
:
Inhabited
A
)
:
Inhabited
(
A
+
B
)
:
=
match
iB
with

populate
y
=>
populate
(
inl
y
)
end
.
Instance
option_inhabited
{
A
}
:
Inhabited
(
option
A
)
:
=
populate
None
.
(** ** Setoid equality *)
(** We define an operational type class for setoid equality. This is based on
(Spitters/van der Weegen, 2011). *)
...
...
theories/numbers.v
View file @
d8445c86
...
...
@@ 25,6 +25,7 @@ Infix "`mod`" := NPeano.modulo (at level 35) : nat_scope.
Instance
nat_eq_dec
:
∀
x
y
:
nat
,
Decision
(
x
=
y
)
:
=
eq_nat_dec
.
Instance
nat_le_dec
:
∀
x
y
:
nat
,
Decision
(
x
≤
y
)
:
=
le_dec
.
Instance
nat_lt_dec
:
∀
x
y
:
nat
,
Decision
(
x
<
y
)
:
=
lt_dec
.
Instance
nat_inhabited
:
Inhabited
nat
:
=
populate
0
%
nat
.
Lemma
lt_n_SS
n
:
n
<
S
(
S
n
).
Proof
.
auto
with
arith
.
Qed
.
...
...
@@ 40,6 +41,8 @@ Definition sum_list_with {A} (f : A → nat) : list A → nat :=
Notation
sum_list
:
=
(
sum_list_with
id
).
Instance
positive_eq_dec
:
∀
x
y
:
positive
,
Decision
(
x
=
y
)
:
=
Pos
.
eq_dec
.
Instance
positive_inhabited
:
Inhabited
positive
:
=
populate
1
%
positive
.
Notation
"(~0)"
:
=
xO
(
only
parsing
)
:
positive_scope
.
Notation
"(~1)"
:
=
xI
(
only
parsing
)
:
positive_scope
.
...
...
@@ 75,6 +78,7 @@ Program Instance N_lt_dec (x y : N) : Decision (x < y)%N :=

_
=>
right
_
end
.
Next
Obligation
.
congruence
.
Qed
.
Instance
N_inhabited
:
Inhabited
N
:
=
populate
1
%
N
.
Infix
"≤"
:
=
Z
.
le
:
Z_scope
.
Notation
"x ≤ y ≤ z"
:
=
(
x
≤
y
∧
y
≤
z
)%
Z
:
Z_scope
.
...
...
@@ 87,6 +91,7 @@ Notation "(<)" := Z.lt (only parsing) : Z_scope.
Instance
Z_eq_dec
:
∀
x
y
:
Z
,
Decision
(
x
=
y
)
:
=
Z
.
eq_dec
.
Instance
Z_le_dec
:
∀
x
y
:
Z
,
Decision
(
x
≤
y
)%
Z
:
=
Z_le_dec
.
Instance
Z_lt_dec
:
∀
x
y
:
Z
,
Decision
(
x
<
y
)%
Z
:
=
Z_lt_dec
.
Instance
Z_inhabited
:
Inhabited
Z
:
=
populate
1
%
Z
.
(** * Conversions *)
(** The function [Z_to_option_N] converts an integer [x] into a natural number
...
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