Documentation

Lean.PrettyPrinter.Delaborator.Basic

The delaborator is the first stage of the pretty printer, and the inverse of the elaborator: it turns fully elaborated Expr core terms back into surface-level Syntax, omitting some implicit information again and using higher-level syntax abstractions like notations where possible. The exact behavior can be customized using pretty printer options; activating pp.all should guarantee that the delaborator is injective and that re-elaborating the resulting Syntax round-trips.

Pretty printer options can be given not only for the whole term, but also specific subterms. This is used both when automatically refining pp options until round-trip and when interactively selecting pp options for a subterm (both TBD). The association of options to subterms is done by assigning a unique, synthetic Nat position to each subterm derived from its position in the full term. This position is added to the corresponding Syntax object so that elaboration errors and interactions with the pretty printer output can be traced back to the subterm.

The delaborator is extensible via the [delab] attribute.

Instances For
    Instances For
      Equations
      • Lean.PrettyPrinter.Delaborator.instInhabitedDelabM = { default := throw default }
      Equations
      Equations
      • Lean.PrettyPrinter.Delaborator.instOrElseDelabM = { orElse := Lean.PrettyPrinter.Delaborator.orElse }
      @[instance 100]
      Equations
      • One or more equations did not get rendered due to their size.
      Equations
      • One or more equations did not get rendered due to their size.
      Instances For
        Equations
        • One or more equations did not get rendered due to their size.
        Instances For
          Equations
          • One or more equations did not get rendered due to their size.
          Instances For

            Evaluate option accessor, using subterm-specific options if set.

            Equations
            Instances For

              Set the given option at the current position and execute x in this context.

              Equations
              • One or more equations did not get rendered due to their size.
              Instances For
                Equations
                Instances For
                  Equations
                  Instances For
                    Equations
                    • One or more equations did not get rendered due to their size.
                    Instances For
                      Equations
                      • One or more equations did not get rendered due to their size.
                      Instances For
                        Equations
                        • One or more equations did not get rendered due to their size.
                        Instances For
                          Equations
                          • One or more equations did not get rendered due to their size.
                          Instances For

                            Annotates the term with the current expression position and registers TermInfo to associate the term to the current expression.

                            Equations
                            • One or more equations did not get rendered due to their size.
                            Instances For

                              Modifies the delaborator so that it annotates the resulting term with the current expression position and registers TermInfo to associate the term to the current expression.

                              Equations
                              Instances For
                                Equations
                                • One or more equations did not get rendered due to their size.
                                Instances For
                                  Equations
                                  • One or more equations did not get rendered due to their size.
                                  Instances For

                                    Creates an identifier that is annotated with the term e, using a fresh position using the HoleIterator.

                                    Equations
                                    • One or more equations did not get rendered due to their size.
                                    Instances For

                                      Enters the body of the current expression, which must be a lambda or forall. The binding variable is passed to d as Syntax, and it is an identifier that has been annotated with the fvar expression for the variable.

                                      Equations
                                      • One or more equations did not get rendered due to their size.
                                      Instances For
                                        Equations
                                        Instances For
                                          Equations
                                          • One or more equations did not get rendered due to their size.
                                          Instances For

                                            Runs the delaborator act with increased depth. The depth is used when pp.deepTerms is false to determine what is a deep term. See also Lean.PrettyPrinter.Delaborator.Context.depth.

                                            Equations
                                            • One or more equations did not get rendered due to their size.
                                            Instances For

                                              Returns true if e is a "shallow" expression. Local variables, constants, and other atomic expressions are always shallow. In general, an expression is considered to be shallow if its depth is at most threshold.

                                              Since the implementation uses Lean.Expr.approxDepth, the threshold is clamped to [0, 254].

                                              Equations
                                              Instances For

                                                Returns true if, at the current depth, we should omit the term and use rather than delaborating it. This function can only return true if pp.deepTerms is set to false. It also contains a heuristic to allow "shallow terms" to be delaborated, even if they appear deep in an expression, which prevents terms such as atomic expressions or OfNat.ofNat literals from being delaborated as .

                                                Equations
                                                • One or more equations did not get rendered due to their size.
                                                Instances For

                                                  Returns true if the given expression is a proof and should be omitted. This function only returns true if pp.proofs is set to false.

                                                  "Shallow" proofs are not omitted. The pp.proofs.threshold option controls the depth threshold for what constitutes a shallow proof. See Lean.PrettyPrinter.Delaborator.isShallowExpression.

                                                  Equations
                                                  • One or more equations did not get rendered due to their size.
                                                  Instances For

                                                    Delaborates the current expression as and attaches Elab.OmissionInfo, which influences how the subterm omitted by is delaborated when hovered over.

                                                    Equations
                                                    • One or more equations did not get rendered due to their size.
                                                    Instances For
                                                      Equations
                                                      • One or more equations did not get rendered due to their size.
                                                      Instances For

                                                        "Delaborate" the given term into surface-level syntax using the default and given subterm-specific options.

                                                        Equations
                                                        Instances For