fix: universe inference for Prop-valued structures/inductives
#2695
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
Thanks for your contribution! Please make sure to follow our Commit Convention. |
arthur-adjedj
force-pushed
the
StructCorrectUniv
branch
2 times, most recently
from
95e4f23 to
c00a093
Compare
github-actions
bot
added
the
toolchain-available
leanprover-community-mathlib4-bot
added a commit
to leanprover-community/mathlib4
that referenced
this pull request
Oct 16, 2023
leanprover-community-mathlib4-bot
added
the
breaks-mathlib
|
digama0
reviewed
Oct 16, 2023
src/Init/Core.lean
Outdated
| @@ -1684,15 +1684,15 @@ axiom ofReduceNat (a b : Nat) (h : reduceNat a = b) : a = b | |||
| `IsAssociative op` says that `op` is an associative operation, | |||
| i.e. `(a ∘ b) ∘ c = a ∘ (b ∘ c)`. It is used by the `ac_rfl` tactic. | |||
| -/ | |||
| class IsAssociative {α : Sort u} (op : α → α → α) where | |||
| class IsAssociative {α : Sort u} (op : α → α → α) : Type where | |||
There was a problem hiding this comment.
IMO these should be Props, this is exactly the kind of issue we are hoping to avoid by changing the default
digama0
reviewed
Oct 16, 2023
src/Init/Prelude.lean
Outdated
| @@ -807,7 +807,7 @@ decidability instance instead of the proposition, which has no code). | |||
| If a proposition `p` is `Decidable`, then `(by decide : p)` will prove it by | |||
| evaluating the decidability instance to `isTrue h` and returning `h`. | |||
| -/ | |||
| class inductive Decidable (p : Prop) where | |||
| class inductive Decidable (p : Prop) : Type where | |||
There was a problem hiding this comment.
This is a bug, it should not infer Prop here because the inductive has two constructors.
There was a problem hiding this comment.
Yes, the current draft makes a hacky tweak to accLevel, which I believe isn't the right solution, as explained in the issue (This is not meant for review just yet). When tweaking mkResultUniverse, I end up getting some kernel errors regarding loose universe variables in sort-polymorphic inductives like PProd, so there's still work to do.
kim-em
added
the
WIP
kim-em
removed
the
breaks-mathlib
arthur-adjedj
force-pushed
the
StructCorrectUniv
branch
from
310d0dd to
41b7323
Compare
arthur-adjedj
force-pushed
the
StructCorrectUniv
branch
2 times, most recently
from
2fb4925 to
59ce249
Compare
arthur-adjedj
changed the title
Prop-valued structures/inductivesProp-valued structures/inductives
leanprover-community-mathlib4-bot
added a commit
to leanprover-community/batteries
that referenced
this pull request
Aug 28, 2024
leanprover-community-mathlib4-bot
added a commit
to leanprover-community/mathlib4
that referenced
this pull request
Aug 28, 2024
leanprover-community-bot
added
the
breaks-mathlib
arthur-adjedj
force-pushed
the
StructCorrectUniv
branch
from
59ce249 to
bfb8937
Compare
arthur-adjedj
force-pushed
the
StructCorrectUniv
branch
from
bfb8937 to
1196faa
Compare
leanprover-community-mathlib4-bot
added a commit
to leanprover-community/batteries
that referenced
this pull request
Sep 3, 2024
leanprover-community-mathlib4-bot
added a commit
to leanprover-community/mathlib4
that referenced
this pull request
Sep 3, 2024
kmill
added a commit
to kmill/lean4
that referenced
this pull request
Sep 29, 2024
…c subsingletons A `Prop`-valued inductive type is a syntactic subsingleton if it has at most one constructor and all the arguments to the constructor are in `Prop`. Such types have large elimination, so they could be defined in `Type` or `Prop` without any trouble, though users tend to expect that such types define a `Prop` and need to learn to insert `: Prop` manually. Currently, the default universe for types is `Type`. This PR adds a heuristic: if a type is a syntactic subsingleton with exactly one constructor, and the constructor has at least one parameter, then the `inductive` command will prefer creating a `Prop` instead of a `Type`. For `structure`, we ask for at least one field. More generally, for mutual inductives, each type needs to be a syntactic subsingleton, at least one type must have one constructor, and at least one constructor must have at least one parameter. Thanks to @arthur-adjedj for the investigation in leanprover#2695. Closes leanprover#2690
kmill
added a commit
to kmill/lean4
that referenced
this pull request
Oct 8, 2024
…c subsingletons A `Prop`-valued inductive type is a syntactic subsingleton if it has at most one constructor and all the arguments to the constructor are in `Prop`. Such types have large elimination, so they could be defined in `Type` or `Prop` without any trouble, though users tend to expect that such types define a `Prop` and need to learn to insert `: Prop` manually. Currently, the default universe for types is `Type`. This PR adds a heuristic: if a type is a syntactic subsingleton with exactly one constructor, and the constructor has at least one parameter, then the `inductive` command will prefer creating a `Prop` instead of a `Type`. For `structure`, we ask for at least one field. More generally, for mutual inductives, each type needs to be a syntactic subsingleton, at least one type must have one constructor, and at least one constructor must have at least one parameter. Thanks to @arthur-adjedj for the investigation in leanprover#2695. Closes leanprover#2690
github-merge-queue bot
pushed a commit
that referenced
this pull request
Oct 8, 2024
…c subsingletons (#5517) A `Prop`-valued inductive type is a syntactic subsingleton if it has at most one constructor and all the arguments to the constructor are in `Prop`. Such types have large elimination, so they could be defined in `Type` or `Prop` without any trouble, though users tend to expect that such types define a `Prop` and need to learn to insert `: Prop`. Currently, the default universe for types is `Type`. This PR adds a heuristic: if a type is a syntactic subsingleton with exactly one constructor, and the constructor has at least one parameter, then the `inductive` command will prefer creating a `Prop` instead of a `Type`. For `structure`, we ask for at least one field. More generally, for mutual inductives, each type needs to be a syntactic subsingleton, at least one type must have one constructor, and at least one constructor must have at least one parameter. The motivation for this restriction is that every inductive type starts with a zero constructors and each constructor starts with zero fields, and stubbed-out types shouldn't be `Prop`. Thanks to @arthur-adjedj for the investigation in #2695 and to @digama0 for formulating the heuristic. Closes #2690
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Closes #2690
External Contribution Guidelines.