With macros you can define new variable binding constructs. That's something I occasionally miss in Haskell.
-- Lennart On Wed, Jan 14, 2009 at 6:48 PM, Jonathan Cast <jonathancc...@fastmail.fm> wrote: > On Wed, 2009-01-14 at 12:39 -0600, Tim Wawrzynczak wrote: >> You're probably right. >> I've played around with LISP macros a little, but it seems >> that most >> of the cases where you would use a macro in LISP you don't >> need one in >> haskell due to lazy evaluation. Although I haven't played >> around with >> them enough to say much one way or another. >> >> Do you know of a particular example where a macro would be a >> big help >> in haskell? >> >> Well, like many good programming tools, Lisp macros are another >> abstraction, but instead of dealing with data, they deal with code. > > Haskell already has a couple of abstraction tools for dealing with code. > One is called `first-class functions'; another is called `lazy > evaluation'. > >> They are a syntactic abstraction. > > What is this good for? I suspect most Lisp macros are parametric in > form, rather than really syntactic; I know that every example of a Lisp > macro I've seen is parametric in form. Parametric macros --- macros > that don't deconstruct their arguments --- don't usually need to be > macros at all in modern functional languages. Do you have an example of > a macro that can't be replaced by higher-order functions and laziness? > >> They're often described as "programs that write programs." > > So are code generators. The most common example of a code generator is > probably YACC --- but Parsec replaces it, with better readability even, > with first-class parsers (built atop first-class functions). > > jcc > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
