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