Loogle!

Result

Found 3 declarations mentioning ExceptT.map.

• ExceptT.map 📋 Init.Control.Except
  {ε : Type u} {m : Type u → Type v} [Monad m] {α β : Type u} (f : α → β) (x : ExceptT ε m α) : ExceptT ε m β
• ExceptT.map.eq_1 📋 Init.Control.Lawful.Instances
  {ε : Type u} {m : Type u → Type v} [Monad m] {α β : Type u} (f : α → β) (x : ExceptT ε m α) : ExceptT.map f x = ExceptT.mk do let a ← x match a with | Except.ok a => pure (Except.ok (f a)) | Except.error e => pure (Except.error e)
• ExceptT.instMonad.eq_1 📋 Init.Control.Lawful.Instances
  {ε : Type u} {m : Type u → Type v} [Monad m] : ExceptT.instMonad = { map := fun {α β} => ExceptT.map, pure := fun {α} => ExceptT.pure, seq := fun {α β} f x => (fun {α β} => ExceptT.bind) f fun y => (fun {α β} => ExceptT.map) y (x ()), seqLeft := fun {α β} x y => (fun {α β} => ExceptT.bind) x fun a => (fun {α β} => ExceptT.bind) (y ()) fun x => (fun {α} => ExceptT.pure) a, seqRight := fun {α β} x y => (fun {α β} => ExceptT.bind) x fun x => y (), bind := fun {α β} => ExceptT.bind }

About

Loogle searches Lean and Mathlib definitions and theorems.

You can use Loogle from within the Lean4 VSCode language extension using (by default) Ctrl-K Ctrl-S. You can also try the #loogle command from LeanSearchClient, the CLI version, the Loogle VS Code extension, the lean.nvim integration or the Zulip bot.

Usage

Loogle finds definitions and lemmas in various ways:

1. By constant:
   🔍 Real.sin
   finds all lemmas whose statement somehow mentions the sine function.

2. By lemma name substring:
   🔍 "differ"
   finds all lemmas that have "differ" somewhere in their lemma name.

3. By subexpression:
   🔍 _ * (_ ^ _)
   finds all lemmas whose statements somewhere include a product where the second argument is raised to some power.

   The pattern can also be non-linear, as in
   🔍 Real.sqrt ?a * Real.sqrt ?a

   If the pattern has parameters, they are matched in any order. Both of these will find List.map:
   🔍 (?a -> ?b) -> List ?a -> List ?b
   🔍 List ?a -> (?a -> ?b) -> List ?b

4. By main conclusion:
   🔍 |- tsum _ = _ * tsum _
   finds all lemmas where the conclusion (the subexpression to the right of all → and ∀) has the given shape.

   As before, if the pattern has parameters, they are matched against the hypotheses of the lemma in any order; for example,
   🔍 |- _ < _ → tsum _ < tsum _
   will find tsum_lt_tsum even though the hypothesis f i < g i is not the last.

If you pass more than one such search filter, separated by commas Loogle will return lemmas which match all of them. The search
🔍 Real.sin, "two", tsum, _ * _, _ ^ _, |- _ < _ → _
would find all lemmas which mention the constants Real.sin and tsum, have "two" as a substring of the lemma name, include a product and a power somewhere in the type, and have a hypothesis of the form _ < _ (if there were any such lemmas). Metavariables (?a) are assigned independently in each filter.

The #lucky button will directly send you to the documentation of the first hit.

Source code

You can find the source code for this service at https://github.com/nomeata/loogle. The https://loogle.lean-lang.org/ service is provided by the Lean FRO.

This is Loogle revision 19971e9 serving mathlib revision bce1d65