I uploaded the module to garden. I have only implemented scaling of single vertical bar ("|"). braket.sty also allows scaling of double vertical bar ("||") and only treating the first | to be special. These are not implemented right now. In case someone needs them, let me know.

The module is available from

http://modules.contextgarden.net/mathsets

Aditya

I also need that. Thank you. Zulkifli