Is there a way to add a socket of a specific type to group nodes? Currently, it seems that they default to grey scalar sockets, and I don't see any way to change their type.

Is there a way to add a socket of a specific type to group nodes? Currently, it seems that they default to grey scalar sockets, and I don't see any way to change their type.

You need to connect the temporary socket (red) to the values you want to make available from outside the group.

When tab out of the group you will have all of them available for wiring with the correct type (indicated bei their color).

Note that you can't edit them later you would need to recreate the group.
X button in the right pane). Therefore it is possible to change the socket type by creating a new one and removing the old one, without the need to re-create it "from scratch" (it will sadly break existing connections on uses of the node, though).
– Suzanne Soy
May 18 '16 at 22:42