Is it possible to define a function once for different argument types in GLSL?

Question

Suppose I have a function such as this,

vec2 myFun(vec2 v){
   return vec2(length(v));
}

Is it possible to avoid defining exactly same functions for vec2 and vec3 -valued arguments and respectively outputs? Or more generally, if my function body only contains other genType functions, can I define it just once for all argument types?

Answer 1

GLSL itself doesn't support this, but you could use a macro to have the preprocessor do the work for you:

#define _(TYPE)\
TYPE myFun(TYPE v){\
    return TYPE(length(v));\
}
// define above functions for gentypes
_(float)_(vec2)_(vec3)_(vec4)

Note that you have to escape line breaks in the macro, so you probably want your host application to stitch it together that way.