`deconstructUnitors`🔗

Definition

Deconstruct a left or right unitor [inverse] morphism.

def

deconstructUnitors (e : Lean.Expr) (eLvl : Lean.Level)
  (left hom : Bool) : Lean.MetaM (Lean.Expr × Lean.Expr)
deconstructUnitors (e : Lean.Expr)
  (eLvl : Lean.Level) (left hom : Bool) :
  Lean.MetaM (Lean.Expr × Lean.Expr)

Code

def deconstructUnitors (e : Expr) (eLvl : Level) (left hom : Bool) :
    MetaM (Expr × Expr) := do
  let args := e.getAppArgs
  let SX := args[args.size - 1]!
  let X ← getTypeFromSFinKer SX
  let ex ← idME X
  let (X₀, x₀Lvl) ← getOriginalType X
  let ex₀ ← constructMeasurableEquiv X₀ x₀Lvl eLvl
  let const_args := [eLvl, x₀Lvl, eLvl, Level.zero]
  let const_name :=
    if left then
      if hom then ``leftUnitor_hom
      else ``leftUnitor_inv
    else
      if hom then ``rightUnitor_hom
      else ``rightUnitor_inv
  let const := mkConst const_name const_args
  let unitor_proof_eq ← mkAppM' const #[SX, ex, ex₀]
  return (← getKernelRHSEqProofType unitor_proof_eq, unitor_proof_eq)

Actions: Source · Open Issue

Meaning last changed in v4.34.0-rc2-1-g439785b (2026-08-23).

Self-contained, with its dependencies inlined and proofs replaced by sorry: download the raw file · open it in the Lean web editor.

Dependency graph

Audit surface: 5 project declarations, 112 external constants

✓ 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.

deconstructUnitors🔗

`deconstructUnitors`🔗