Learning.Round.mapFeedback
From the authors
Transport the feedback of a round.
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๐ : Type u_1 -
๐ : Type u_4 -
๐จ : Type u_7 -
๐จ' : Type u_8
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f : ๐จ โ ๐จ' -
r : Round ๐ ๐ ๐จOne round of interaction: an observation, then an action, then a feedback.
Round ๐ ๐ ๐จ'map id id f rLearning.Round : Type u_5 โ Type u_6 โ Type u_7 โ Type (max u_5 u_7 u_6)One round of interaction: an observation, then an action, then a feedback.Go to its page
Learning.Round.map : {๐ : Type u_1} โ
{๐' : Type u_2} โ
{๐ : Type u_4} โ
{๐' : Type u_5} โ
{๐จ : Type u_7} โ
{๐จ' : Type u_8} โ (๐ โ ๐') โ (๐ โ ๐') โ (๐จ โ ๐จ') โ Learning.Round ๐ ๐ ๐จ โ Learning.Round ๐' ๐' ๐จ'Transport a round along maps of the observation, the action and the feedback.Go to its page
id : {ฮฑ : Sort u} โ ฮฑ โ ฮฑThe identity function. `id` takes an implicit argument `ฮฑ : Sort u` (a type in any universe), and an argument `a : ฮฑ`, and returns `a`. Although this may look like a useless function, one application of the identity function is to explicitly put a type on an expression. If `e` has type `T`, and `T'` is definitionally equal to `T`, then `@id T' e` typechecks, and Lean knows that this expression has type `T'` rather than `T`. This can make a difference for typeclass inference, since `T` and `T'` may have different typeclass instances on them. `show T' from e` is sugar for an `@id T' e` expression.
Code
abbrev Round.mapFeedback (f : ๐จ โ ๐จ') (r : Round ๐ ๐ ๐จ) : Round ๐ ๐ ๐จ' := Round.map id id f r
New in v4.34.0-rc2-74-ge05e4f3 (2026-09-10), and its meaning has not changed since.
Self-contained, with its dependencies inlined and proofs replaced by sorry: download the raw file ยท open it in the Lean web editor.
Dependency graph
Audit surface: 5 project declarations, 5 external constants
โ Proved: no sorry anywhere in its closure
This is the tool's own reading of one build's recorded axioms, and it is not robust against an author who wants it to pass. Checking meant to be relied on should go through Comparator, which replays the proof through the kernel from an export against an explicit list of permitted axioms.