[NTG-context] issue with custom hyphenator

[Pablo Rodriguez]

Dear list,

I have just copied this from
https://www.pragma-ade.com/general/manuals/languages-mkiv.pdf#page=23:

  \startluacode
      local subset = {
          a = true,
          e = true,
          i = true,
          o = true,
          u = true,
          y = true,
      }

      languages.hyphenators.traditional.installmethod("test",
          function(dictionary,word,n)
              local t = { }
              for i=1,#word do
                  local w = word[i]
                  if subset[w] then
                      t[i] = {
                          before = "<" .. w,
                          after  = w .. ">",
                          left   = false,
                          right  = false,
                      }
                  else
                      t[i] = false
                  end
              end
              return t
          end
      )
  \stopluacode

  \definehyphenationfeatures
    [demo]
    [alternative=test]
  \setuphyphenation[method=traditional]

  \starttext
  %\righthyphenmin=-1
  \sethyphenationfeatures[demo]
  \hsize\zeropoint
  coming anaback
  \stoptext

Using current latest (from 2023.02.07 19:06), I get:

  c<o
  o>ing
  an<a
  a>ack

I’m missing m and b in the hyphenated words.

I’m afraid that the hyphenator is all Greek to me.

Is there any reason why letters are lost in hyphenation?

I’m afraid (I think) I might have hit a bug.

Many thanks for your help,

Pablo