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doc: improve documentation of Init.Coe

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Delete misleading explanations of `CoeFun` and `CoeSort`, and fix the
grammar in the documentation of `Init.Coe`.
This commit is contained in:
Bulhwi Cha 2023-02-12 15:01:25 +09:00 • committed by Leonardo de Moura
parent bc841809c2
commit b3eeeffd90
1 changed files with 10 additions and 7 deletions
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17
src/Init/Coe.lean
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@ -101,8 +101,9 @@ These classes should be implemented for coercions:
`f` does not have a function type.
`CoeFun` instances apply to `CoeOut` as well.
* `CoeSort α β` is a coercion to a sort. `β` must be a universe, and if
`a : α` appears in a place where a type is expected, like `(x : a)` or `a → a`.
* `CoeSort α β` is a coercion to a sort. `β` must be a universe, and this is
triggered when `a : α` appears in a place where a type is expected, like
`(x : a)` or `a → a`.
`CoeSort` instances apply to `CoeOut` as well.
On top of these instances this file defines several auxiliary type classes:
@ -254,8 +255,9 @@ instance : CoeT α a α where coe := a
/--
`CoeFun α (γ : α → Sort v)` is a coercion to a function. `γ a` should be a
(coercion-to-)function type, and this is triggered whenever an element
`f : α` appears in an application like `f x` which would not make sense since
`f` does not have a function type. This is automatically turned into `CoeFun.coe f x`.
`f : α` appears in an application like `f x`, which would not make sense since
`f` does not have a function type.
`CoeFun` instances apply to `CoeOut` as well.
-/
class CoeFun (α : Sort u) (γ : outParam (α → Sort v)) where
/-- Coerces a value `f : α` to type `γ f`, which should be either be a
@ -267,9 +269,10 @@ attribute [coe_decl] CoeFun.coe
instance [CoeFun α fun _ => β] : CoeOut α β where coe a := CoeFun.coe a
/--
`CoeSort α β` is a coercion to a sort. `β` must be a universe, and if
`a : α` appears in a place where a type is expected, like `(x : a)` or `a → a`,
then it will be turned into `(x : CoeSort.coe a)`.
`CoeSort α β` is a coercion to a sort. `β` must be a universe, and this is
triggered when `a : α` appears in a place where a type is expected, like
`(x : a)` or `a → a`.
`CoeSort` instances apply to `CoeOut` as well.
-/
class CoeSort (α : Sort u) (β : outParam (Sort v)) where
/-- Coerces a value of type `α` to `β`, which must be a universe. -/