`checkUnitors`🔗

Definition

Check if a kernel expression corresponds to a left or right unitor.

def

checkUnitors (κ : Lean.Expr) (offset : ℕ) (prod : Lean.Name) :
  Lean.MetaM Bool
checkUnitors (κ : Lean.Expr) (offset : ℕ)
  (prod : Lean.Name) : Lean.MetaM Bool

Code

def checkUnitors (κ : Expr) (offset : Nat) (prod : Name) : MetaM Bool := do
  let κ := κ.consumeMData
  if !κ.isAppOf ``Kernel.map then
    return false
  let args := κ.getAppArgs
  let fn := args[args.size - 1]!
  let idKernel := args[args.size - 2]!
  if !fn.isAppOf prod then
    return false
  if !idKernel.isAppOf ``Kernel.id then
    return false
  let (src, _, _) ← getTypesFromKernel κ
  match src.getAppFn with
  | Expr.const ``Prod _ =>
    let args := src.getAppArgs
    if args.size < 2 then
      return false
    let punit? := args[offset]!
    match punit?.getAppFn with
    | Expr.const ``PUnit _ | Expr.const ``Unit _ => return true
    | _ => return false
  | _ => return false

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: 1 project declarations, 109 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.

checkUnitors🔗

`checkUnitors`🔗