Fixing value of a sampled variable inside a loop to a constant

Say, I want to fix the value of a variable inside a loop to a constant, although this could change when the constant is changed in the call to a function outside the loop; how do I specify such a scenario, if possible?

CODE:

real a;
real a_const;
real b;

a ~ std_normal();
b ~ std_normal();

a_const = a;
for (i in 1:10) {
  c = b*a_const; // value of a_const should be constant, for b it can change
}

Can I do something as a work about to specify this?
I understand that inside the loop before the product is assigned to c; b and a must be sampled.
Please correct me if wrong.

Welcome to the forums! Would you be able to clarify your aim a little bit here?

Is there a reason that you can’t use:


for (i in 1:10) {
  c = b*a; 
}

What do you mean by a constant value here?