__ __ __ __ ____ ___ __________________________________________ || || || || || || ||__ Hugs 1.3c: The Haskell User's Gofer System ||___|| ||__|| ||__|| __|| Copyright (c) Mark P Jones, ||---|| ___|| The University of Nottingham, 1994-1998. || || Report bugs to hugs-bugs@haskell.org || || [March 1998] __________________________________________ This is the Readme file for Hugs 1.3c. Hugs 1.3c is an interpreter that provides an almost complete implementation of Haskell 1.3; the only significant feature that is not supported is the module system. Many Hugs users will prefer to use Hugs 1.4, which is a joint project between the groups at Nottingham and Yale, and a direct successor to Hugs 1.3. Large parts of the type checker in Hugs 1.3c have been rewritten to give greater compatability with Haskell and to eliminate the special handling of overloading that was inherited from the implementation of Gofer. However, there are a number of areas in which the changes in Hugs 1.3c will be more visible to users, including: - Overloading: multiple parameter classes, unrestricted contexts, overlapping instances (if the +o command line option is used). - Rank 2 polymorphism: primitives, user defined functions, class members, and data constructors can have arguments with polymorphic types. - Existential types: Components of data structures may have types involving existentially quantified variables. - Explicitly scoped type variables (in the style of SML): Patterns may include type annotations, and variables appearing in these annotations will be visible within the scope of any variables defined in the pattern. Hugs 1.3c provides a preview of features that are expected to appear in future versions of Hugs, including, in the near future, Hugs 1.4. Hugs 1.3c should be considered as *experimental* software: it may contain bugs and may not provide complete implementations of all features. Moreover, it is likely that the set of features in this release will change, and that restrictions in this release may be either tightened or relaxed in future versions. If you need a more stable, or more fully tested version of Hugs, then you are strongly encouraged to use either Hugs 1.3b, or the latest release of Hugs 1.4 (The January 1998 release, at the time of writing). Your feedback, comments, suggestions and bug reports are most welcome! Please note however that *all* bug reports must be sent to hugs-bugs@haskell.org, otherwise I may not see them. Similarly, any other queries about Hugs should be sent to hugs-users@haskell.org. ______________________________________________________________________________ Mark P. Jones mpj@cs.nott.ac.uk http://www.cs.nott.ac.uk/Department/Staff/mpj/index.html Department of Computer Science, University of Nottingham, England NG7 2RD ______________________________________________________________________________