[NTG-context] Treat last element in a commalist differently

2 Jun 2006

      Hi,
  I am trying to write a macro so that

\SEQ X[1,2,3] expands to $X_1, X_2, X_3$
\SEQ X[1-N] expands to $X_1, \dots, X_N$
and
\SEQ X expands to ${\bf X}$.

So far I have

\def\SEQ#1%
   {\dodoubleempty\doSEQ[#1]}

\def\doSEQ[#1][#2]%
{\ifsecondargument \mathematics{\processcommalist[#2]{\dodoSEQ{#1}}}
\else \mathematics{\bold{#1}}\fi}

\def\dodoSEQ#1#2%
   {#1_{#2},}

\starttext
\SEQ X[1,2,3] is part of \SEQ X.
\stoptext

There is an extra comma at the end. That is,

\SEQ X[1,2,3] expands to $X_1,X_2,X_3,$
                                     ^^^

How can I treat the last element of a commalist differently?

Thanks,
Aditya

[NTG-context] Treat last element in a commalist differently

Aditya Mahajan