What are the equality operators in Stan functions?

Modeling
1

Please excuse my newbie question,

model {
  N=10
  theta = [0.2,0.5,0.3]
  n ~ binomial(N, theta)
  y ~ (how to write the formula?); 
}

I want y ~ distribution1 if n=0, distribution2 if n>0.

If there is an “equality operator” I might be able to write
y ~ (n==0)*distribution1 + (n!=0)*distribution2
but I cannot find an equality operator or any other logic operators (and, or, xor etc) in the reference.

How is the STANic way to write such a distribution? Many Thanks!

2

All of the standard logical flow operators are available, so you would do something like:

if (n > 0) {
  ...
} else {
  ...
}
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