As I understand it, the problem there is that most interesting things are recursive functions, and one must decide what can be evaluated at compile time. The idea went somewhere but never made it into the mainstream: https://ndmitchell.com/downloads/paper-a_supercompiler_for_core_haskell-01_may_2008.pdf <https://ndmitchell.com/downloads/paper-a_supercompiler_for_core_haskell-01_may_2008.pdf>
Cheers, Vanessa > On Jan 8, 2020, at 12:41 PM, Raul Miller <rauldmil...@gmail.com> wrote: > > Haskell's lazy evaluation also offers significant opportunities for > partial compile time (aka "eager") evaluation of expressions, which > tends to result in blazing fast run-time (since the calculations were > already completed, or to some degree). > > The downside has to do with debugging in some of the remaining cases. > But people experienced with a language tend to learn to avoid many of > its pain points. > > Thanks, > > -- > Raul > > On Wed, Jan 8, 2020 at 1:32 PM Vanessa McHale <vamch...@gmail.com > <mailto:vamch...@gmail.com>> wrote: >> >> Haskell’s lazy evaluation is also more complex than it might seem at first >> glance: it’s not quite the same as non-strictness, and in particular in a >> proper lazy language various data structures are more efficient due to >> caching &c. >> >> Cheers, >> Vanessa >> >>> On Jan 8, 2020, at 12:28 PM, Raul Miller <rauldmil...@gmail.com >>> <mailto:rauldmil...@gmail.com>> wrote: >>> >>> On Tue, Jan 7, 2020 at 8:24 PM Raoul Schorer <raoul.scho...@gmail.com >>> <mailto:raoul.scho...@gmail.com> <mailto:raoul.scho...@gmail.com >>> <mailto:raoul.scho...@gmail.com>>> wrote: >>>> 'Is it possible to define infinite data structures and operate on them in >>>> J?' >>> >>> There are an infinity of infinities and any useful approach at >>> representing infinities can only handle a finite subset. >>> >>>> For example, take the first ten elements of an infinite list, as in >>>> Haskell. >>>> The 'F.' primitive family seems promising indeed. >>> >>> You can think of J's i. (when used without a left argument) as >>> representing an infinite list and its right argument as specifying how >>> much of that infinite list you want. And, you can use functions >>> incorporating i. to extend the possibilities. >>> >>> That said, Haskell is (in this context) more LISP like: with a bias >>> towards micro-recursions and a bias away from numeric representations >>> of size. J can indeed emulate that, but performance tends to suffer if >>> or when you don't understand how to map the micro-recursions onto >>> arithmetic. (Or, more simply: Haskell is a better Haskell than J is.) >>> >>> Does this help? >>> >>> Thanks, >>> >>> -- >>> Raul >>> >>> >>>> >>>> Le mer. 8 janv. 2020 à 01:56, Henry Rich <henryhr...@gmail.com> a écrit : >>>> >>>>> I don't understand the task at all. You might look in NuVoc for $:, F. >>>>> etc., and M. >>>>> >>>>> Henry Rich >>>>> >>>>> On 1/7/2020 7:51 PM, Raoul Schorer wrote: >>>>>> Hi, >>>>>> >>>>>> Implementing Minikanren <http://minikanren.org/> in J by translating >>>>> from >>>>>> Scheme, I stumbled on the following: >>>>>> I have a Scheme procedure 'fives' >>>>>> < >>>>> https://github.com/jasonhemann/microKanren/blob/master/microKanren-test-programs.scm >>>>>> >>>>>> that is passed a vector and yields a procedure that then takes a pair. >>>>>> ((fives (vector 0)) '(() . 0)) >>>>>> >>>>>> My problem is that this then evaluates to a pair data -- procedure: >>>>>> ((((#(0) . 5)) . 0) . #<procedure at microKanren-test-programs.scm:677>) >>>>>> >>>>>> The second member of the pair (the procedure) is then evaluated on demand >>>>>> to yield another similar structure of length n+1, therefore allowing the >>>>>> lazy evaluation of this infinite "stream". >>>>>> >>>>>> Is switching to iterative/eager eval the only realistic way? >>>>>> Can someone help me with lazy eval of infinite structures in J, or give >>>>> me >>>>>> pointers to resources on the topic? >>>>>> >>>>>> Thanks! >>>>>> Raoul Schorer >>>>>> ---------------------------------------------------------------------- >>>>>> For information about J forums see http://www.jsoftware.com/forums.htm >>>>> >>>>> ---------------------------------------------------------------------- >>>>> For information about J forums see http://www.jsoftware.com/forums.htm >>>>> >>>> ---------------------------------------------------------------------- >>>> For information about J forums see http://www.jsoftware.com/forums.htm >>> ---------------------------------------------------------------------- >>> For information about J forums see http://www.jsoftware.com/forums.htm >>> <http://www.jsoftware.com/forums.htm> <http://www.jsoftware.com/forums.htm >>> <http://www.jsoftware.com/forums.htm>> >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> <http://www.jsoftware.com/forums.htm> > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > <http://www.jsoftware.com/forums.htm> ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
