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Mathlib.Data.Option.Defs

Extra definitions on Option #

This file defines more operations involving Option α. Lemmas about them are located in other files under Mathlib/Data/Option/. Other basic operations on Option are defined in the core library.

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def Option.traverse {F : Type u → Type v} [Applicative F] {α : Type u_1} {β : Type u} (f : α → F β) :
Option α → F (Option β)

Traverse an object of Option α with a function f : α → F β for an applicative F.

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    def Option.elim' {α : Type u_1} {β : Type u_2} (b : β) (f : α → β) :
    Option α → β

    An elimination principle for Option. It is a nondependent version of Option.rec.

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      @[simp]
      theorem Option.elim'_none {α : Type u_1} {β : Type u_2} (b : β) (f : α → β) :
      Option.elim' b f none = b
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      @[simp]
      theorem Option.elim'_some {α : Type u_1} {β : Type u_2} {a : α} (b : β) (f : α → β) :
      Option.elim' b f (some a) = f a
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      @[simp]
      theorem Option.elim'_none_some {α : Type u_1} {β : Type u_2} (f : Option α → β) :
      Option.elim' (f none) (f ∘ some) = f
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      theorem Option.elim'_eq_elim {α : Type u_3} {β : Type u_4} (b : β) (f : α → β) (a : Option α) :
      Option.elim' b f a = a.elim b f
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      @[reducible, inline, deprecated "Use `Option.get!` (which will panic on `none`) or `Option.getD` (which takes an explicit default value)." (since := "2026-01-05")]
      abbrev Option.iget {α : Type u_1} [Inhabited α] :
      Option α → α

      Inhabited get function. Returns a if the input is some a, otherwise returns default.

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        @[deprecated "Use `Option.getD`." (since := "2026-01-05")]
        theorem Option.iget_some {α : Type u_1} [Inhabited α] {a : α} :
        (some a).iget = a