Thank you all for your help! It works perfectly now.

No, it won't automatically convert.

If you want the data type's "zero" value, you can do VuoGenericType1_makeFromJson(NULL). This returns 0; (0,0); (0,0,0); or (0,0,0,0) as needed.

For non-zero values, one way to do it is demonstrated in the vuo.math.multiply.list.2 node class's source code. The nodeEvent function calls a (placeholder) function named VuoGenericType1_make1, which is intended to return the "one" value for the appropriate data type. The node class's source code defines a version of the function for each numeric data type — VuoInteger_make1 that returns 1, VuoPoint2d_make1 that returns (1,1), etc. It's long-winded but it works.

When your generic node class is specialized to a data type, VuoGenericType1_scale is replaced by the function for that data type. For example, when you add a Scale List node to the canvas and choose Set Data Type > Real, the call to VuoGenericType1_scale in that node is replaced with VuoReal_scale (documentation).

It's actually just a text replacement. Everywhere in the node class's source code, the string VuoGenericType1 is replaced with VuoReal.

The available variations of the scale function are: VuoInteger_scale, VuoReal_scale, VuoPoint2d_scale, VuoPoint3d_scale, VuoPoint4d_scale. While there's no entry for VuoGenericType1_scale in the API documentation since it's not an actual function, there are entries for each of these variations.

Thanks for the great info Jaymie (@jstrecker)! As always it looks like Apple has pressed fast forward on the EOL of OpenGL. Hopefully it will be positive for the industry, and for Vulkan (which didn't look like it was gaining traction on MacOS). All I know about Vulkan vs OpenGL is that it's very different, very low level, and not always faster (for high resolution outputs no; but for 1080 much faster).

(When looking at game benchmarks etc)

UPDATE: Just been playing with the 'Vulkan Traiangle' tutorials... looks like I am wrong, and Vulkan can swap out shaders on the fly, (at least if I recompile the shaders obviously...) Having a default way to compile shaders (with error feedback) is a nice change to the silence that was GLSL.