HBC for Haskell 1.3

Haskell 1.3

• Qualified names.
  The old renaming stuff is gone and instead names can be qualified my their module to make them unique. E.g.

        import M(x)
        import N(x)
        y = M.x + N.x
        

• Constructor classes.
  Constructors classes really means that type variables of higher kinds are allowed (e.g. ranging over type constructors such as List). They enable the definition of a monad class (which is in the Prelude). The monad bind operator is called >>= and the unit return. There is also special syntax for monad expressions using the new keyword do. E.g.

        l = do
              x <- [1 .. 4]
              y <- [2 .. 3]
              return (x*y)
        

  l will be the list [2,3,4,6,6,9,8,12]
• New I/O system.
  The I/O was really what triggered the 1.3 work, but it is now just one of several major changes. The I/O now uses a monadic style. E.g.

        main =
            do
              putStr "Hello\n"
              putStr "Give a file name\n"
              name <- getLine
              file <- readFile name
              putStr "OK, here it is:\n"
              putStr file
        

• Records.
  Haskell 1.3 provides a very simple form of records. They are really syntactic sugar for ordinary data types. E.g.

        data Date = Date{ year::Int, month::Int, day::Int }
        xmasDay = Date{ day<-25, year<-1995, month<-12 }  -- record creation
        nextYear = year xmasDay + 1                       -- field extraction
        nextXmas = xmasDay{ year<-nextYear }              -- record "update"
        

HBC

There are still problems lurking (especially in the qualified name implementation), but it seems to work mostly. Please try it out if you feel like it.

WARNING! Do not mix code compiled with and without the 1.3 flag! Hbc gives you a few extras (like calling C), but I've not documented these yet.

If you have any problems just mail me.