Documentation

Mathlib.Tactic.Set

The set tactic #

This file defines the set tactic and its variant set!.

set a := t with h is a variant of let a := t. It adds the hypothesis h : a = t to the local context and replaces t with a everywhere it can. set a := t with ← h will add h : t = a instead. set! a := t with h does not do any replacing.

source
def Mathlib.Tactic.setArgsRest :
Lean.ParserDescr
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    source
    def Mathlib.Tactic.setTactic :
    Lean.ParserDescr

    set a := t with h is a variant of let a := t. It adds the hypothesis h : a = t to the local context and replaces t with a everywhere it can.

    set a := t with ← h will add h : t = a instead.

    set! a := t with h does not do any replacing.

    example (x : Nat) (h : x + x - x = 3) : x + x - x = 3 := by
  set y := x with ← h2
  sorry
/-
x : Nat
y : Nat := x
h : y + y - y = 3
h2 : x = y
⊢ y + y - y = 3
-/
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    Instances For
      source
      def Mathlib.Tactic.tacticSet!_ :
      Lean.ParserDescr

      set a := t with h is a variant of let a := t. It adds the hypothesis h : a = t to the local context and replaces t with a everywhere it can.

      set a := t with ← h will add h : t = a instead.

      set! a := t with h does not do any replacing.

      example (x : Nat) (h : x + x - x = 3) : x + x - x = 3 := by
  set y := x with ← h2
  sorry
/-
x : Nat
y : Nat := x
h : y + y - y = 3
h2 : x = y
⊢ y + y - y = 3
-/
      Equations
      • One or more equations did not get rendered due to their size.
      Instances For