1((function dFdx
2   (signature float
3     (parameters
4       (declare (in) float p))
5     ((return (expression float dFdx (var_ref p)))))
6
7   (signature vec2
8     (parameters
9       (declare (in) vec2 p))
10     ((return (expression vec2 dFdx (var_ref p)))))
11
12   (signature vec3
13     (parameters
14       (declare (in) vec3 p))
15     ((return (expression vec3 dFdx (var_ref p)))))
16
17   (signature vec4
18     (parameters
19       (declare (in) vec4 p))
20     ((return (expression vec4 dFdx (var_ref p)))))
21))
22