El mié, 24 de mar. de 2021 a la(s) 16:47, Hans Hagen (j.hagen@xs4all.nl)
escribió:

> On 3/24/2021 6:33 PM, Jairo A. del Rio wrote:
> > Hi, Hans. Here's my (miserably failing) attempt:
> >
> > \definedataset[nicedata]
> >
> > \starttext
> >
> > \startluacode
> >
> > local name = "nicedata"
> >
> >
> > -- For exposition only
> >
> > local function dofactorial(n)
> >
> > local function inner(c,m)
> >
> > if m<2 then return c end
> >
> > return inner(c*m, m-1)
> >
> > end
> >
> > return inner(1,n)
> >
> > end
> >
> >
> > local function factorial(n)
> >
> > local stringn = tostring(n)
> >
> > if job.datasets.collected[name] then
> >
> > return job.datasets.collected[name].factorial[stringn]
> >
> > else
> >
> > local mydata = {[stringn] = tostring(dofactorial(n))}
> >
> > job.datasets.setdata{
> >
> > name = name,
> >
> > tag = "factorial",
> >
> > data = mydata
> >
> > }
> >
> > return mydata[stringn]
> >
> > end
> >
> > end
> >
> >
> > interfaces.implement{
> >
> > name = "factorial",
> >
> > public = true,
> >
> > arguments = {"string"},
> >
> > actions = {tonumber, factorial, context}
> >
> > }
> >
> >
> > \stopluacode
> >
> > \factorial{7}
> >
> > \stoptext
> >
> >
> > What happens is that, in each run, both the first and the second
> > conditions are met, so the compilation is twice as slow, the opposite
> > result of what I meant to do. How do I fix that?
>
> \definedataset[nicedata]
>
> \starttext
>
> \startluacode
>
> local function dofactorial(n)
>         local function inner(c,m)
>                 if m < 2 then
>              return c
>          else
>              return inner(c*m, m-1)
>          end
>         end
>         return inner(1,n)
> end
>
> local function factorial(n)
>      local data = job.datasets.getdata("factorials","list")
>      if not data then
>          data = { }
>      end
>      local f = data[n]
>      if not f then
>                 f = dofactorial(n)
>          data[n] = f
>      end
>      job.datasets.setdata {
>          name = "factorials",
>          tag  = "list",
>          data = data
>      }
>      return f
> end
>
> interfaces.implement{
>         name      = "factorial",
>         public    = true,
>         arguments = { "integer" },
>         actions   = { factorial, context }
> }
>
> \stopluacode
>
> \dorecurse {20} {
>      \factorial #1 \relax
> }
>
> \stoptext
>
>
It does exactly what I need. It's good to know datasets can be directly
generated, too. Thank you a lot!


> but you probably don't gain much as these factorials are not that slow
> (if you use them many times in a document you can just cache them)
>
>
It was only a toy example. I intend to work with way larger numbers. :)


> Hans
>
>
> -----------------------------------------------------------------
>                                            Hans Hagen | PRAGMA ADE
>                Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>         tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
> -----------------------------------------------------------------
>

Best regards,

Jairo