Building Programatica

• Implementation of tools
• Front-end for Haskell 98

People

• Thomas Hallgren
• Iavor Diatchki
• ...

Previous work (before Sept 10th, 2001)

• Module system
  • Careful reading of the Module section of the Haskell 98 report
  • Results:
    • a clarification of the report
    • an implementation
• Extensible type checker for Haskell 98
• Translation of Haskell to the proof editor Alfa

Progress since last visit (Sept 10th 2001)

• Integration of module system implementation in the front-end
• A new lexical analyzer for Haskell
• Translation of Haskell to HTML
• StripComments
• Support for P logic
• PFE - a front-end framework
• PFE Haskell Browser
• Publications

Integration of module system implementation in the front-end

Processing multi-module Haskell programs is now easy

• Operator precedences
• Scoping
• Type checking
• Translation to Alfa

A new lexical analyzer for Haskell

• The old lexer was hand-written, clumsy and buggy
• The new one is split into two main parts
  • A lexical grammar specifications
    • A simple transliteration of the grammar in the Haskell report
  • A reusable regular expression compiler
    • Based on standard text book methods
• All implemented in Haskell 98

Translation of Haskell to HTML

• Syntax highlighting
• Information pop-ups
• Hyperlinks to definitions
• Preserved comments and layout
  • (by using the new lexer)
• Example: the new Lexer for Haskell

StripComments

• We released a simple tool that strips comments and white space from Haskell 98 programs
  • (Again, based on the new lexical analyzer)
• It was asked for on the Haskell mailing list
• Useful when measuring code size

Support for P logic

• Extension of Haskell 98
  • Predicate definitions
  • Assertions
• Parsing, pretty printing, type checking

PFE - a front-end framework

• All the front-end functionality has been collected in an extensible framework
• Used mainly through a command line interface
  • Command line interface inspired by CVS
  • Built-in make(1)-like functionality
    • (Dependencies between modules are detected automatically)
• Extensible in several dimensions
  • Language extensions
  • New commands
  • Extended internal state

PFE Haskell Browser

• A Haskell browser based on the PFE framework
• Similar to the HTML translation of Haskell
  • Syntax highlighting
  • Navigation
• Can type check and display types
• Can be developed
  • to a graphical user interface to the PFE frame-work
  • from a browser to an editor
• In progress: support for certificates

Publications

• "A Formal Specification of the Haskell 98 Module System"
  • Iavor S. Diatchki, Mark P. Jones, Thomas Hallgren
  • A paper submitted to the 2002 Haskell Workshop
• "A Lexer for Haskell in Haskell"
  • Thomas Hallgren
  • A talk presented at the Haskell Implementers Meeting, Portland, January 2002

What's next

• Integrate support for certificates in the PFE framework
• More work on translation of Haskell and the P logic to theorem provers
• Polish off parts of the tools and release them to the Haskell community
  • Tools often asked for (that we could implement with little effort):
    • Replace layout with explicit braces and semi-colons
    • Transform away the module system
      • (combining many modules into one)
    • Transform away overloading
    • Documentation tools

The end

Questions?