Aditya Mahajan
\def\lambdabar{\lambda\kern-1ex\raise0.65ex\hbox{-}}
Is this the canonical name for the glyph used by AMS?
Good question. The AMS files don't seem to have it (the symbol is hardly used by mathematicians). But revtex4 defines it (for latex), in /usr/local/texlive/2013/texmf-dist/tex/latex/revtex4/revsymb.sty An example of using it: \documentclass{revtex4-1} \begin{document} $\lambdabar$ \end{document}
The right way is to update char-def.lua as
{ adobename="lambdastroke", category="ll", description="LATIN SMALL LETTER LAMBDA WITH STROKE", direction="l", linebreak="al", mathclass="variable", mathname="lambdabar", unicodeslot=0x019B, },
I have put that in and ran 'context --make' pending the font update.
The easiest solution will be to file a bug report with the TeX Gyre project. This is an easy glyph to add.
I'll do that. If you know of it, could you point me to their bug tracker (or best way to file a bug report)? I roamed the GUST site without finding it.
Otherwise, you can use a different font as fall back for lambdabar, but that will not match the regular lambda from Palatino. If you create the glyph on your own, as in your definition above, then you have to play around with the length of the bar to make make it "pretty".
That seems to be what revtex does (it has quite a complicated definition). -Sanjoy