Given the following declarations:

SinOsc s0;

SqrOsc s1;

TriOsc s2;

The following gives an error:

[s0, s1, s2] @=> UGen A[];
$ ... cannot resolve operator '=>' on types 'Osc[]' and 'UGen[]'...

But the following works fine:

[s0, s1, s2] @=> Osc A[];

It is not a problem, but would like to understand this behaviour. It would seem that assigning to UGen[] would be ok because it looks like a superclass of Osc[].

Aaah! Is this to do with co/contra-variance?