Inravina

A portable and extensible Common Lisp pretty printer.

This is a work in progress and not ready to replace the pretty printer in an existing Common Lisp implementation. Most of the pretty printer interface and functionality has been implemented. If you want to kick the tires and light the fires than continue reading!

Requirements

ABCL, Clasp, ECL, and SBCL is the only current implementations that this system has been tested on. The intention is to include this as the stock pretty printer in SICL eventually.

In addition to a clone of this repository in a location that is discoverable by ASDF you will also need a clone of nontrivial-gray-streams and Incless.

Usage

The core functionality is in the inravina package, but the Common Lisp-like interface of pprint-newline, pprint-dispatch is in the inravina-extrinsic package and system. To call pprint on a form try the following in SBCL:

* (asdf:load-system :inravina-extrinsic)
T
* (incless-extrinsic:pprint '(loop for i in '(a b c) 
                                    unless (eq i b) do (stuff i) (quux i) and collect i))

(LOOP FOR I IN '(A B C)
      UNLESS (EQ I B)
        DO (STUFF I)
           (QUUX I)
        AND COLLECT I)

Inravina can also replace replace an implementation's pretty printer. This is done with the inravina-intrinsic system. Because pretty printer works with PRINT-METHOD and must participate in circle detection it must be coupled with the the printer and to some extent with FORMAT. This is done via Incless which has its own intrinsic/extrinsic interface. In the case of replacing the pretty printer of an implementation, Inravina will interface to the printer via the incless-native system. To load all the required systems along with the required glue code one would use the inravina-shim system.

* (asdf:load-system :inravina-shim)
T
* (pprint '(loop for i in '(a b c) 
                 unless (eq i b) do (stuff i) (quux i) and collect i))

(LOOP FOR I IN '(A B C)
      UNLESS (EQ I B)
        DO (STUFF I)
           (QUUX I)
        AND COLLECT I)

There are also some examples of pretty printing with cl-pdf and McCLIM in the examples directory.

Core Functionality

Almost everything works currently. There are probably bugs abound and nothing has been optimized yet. The dispatch tables are functional but very inefficient. There is a variety of form specific printers but not all forms that need a specific printer in the common-lisp package have been covered yet.

In the case of no available printer in the dispatch table for function or macro calls there is a fallback printer. This printer will use introspection on the appropriate lambda list declaration to determine non-key argument counts, body forms, and embedded lambda list desctructuring arguments for macros. Given that information it will attempt to do things like keeping key-values together on a single line or printing body forms correctly, etc.

Extended Functionality

Inravina is being developed with a "client" extensibility design pattern. It is also being designed with an eye to correct shortcomings in the original XP algorithm.

Some extended functionality is already available. Specifically, Inravina can typeset code using proportional fonts. For an sample of this see the PDF code in the examples directory.

Additionally, font styles can be injected into the instruction sequence normally created by pprint-logical-block, pprint-newline, pprint-tab, pprint-indent and calls to write-char or write-string on the pretty stream. A sample of this being done is available in the McCLIM code in the examples directory.