I’m struggling to understand what the new (2.33.1) version of cmdstan expects from me.

I have code like this in the `functions`

block

```
real logFunction(int k, real[] pars){
real r = pars[1];
real w = pars[2];
real p = pars[3];
real s = pars[4];
real ans = lbin(s, k, p) + size_lpmf(k | r, w);
return(ans);
}
```

which gives

```
Error in '/tmp/Rtmpk6Sttv/model-60c058a9b77d.stan', line 4, column 21: Declaration
of arrays by placing brackets after a type was removed in Stan 2.33.0.
Instead use the array keyword before the type. This can be changed
automatically using the auto-format flag to stanc
```

OK. So I then change to

```
real logFunction(int k, array[4] real pars){
real r = pars[1];
real w = pars[2];
real p = pars[3];
real s = pars[4];
real ans = lbin(s, k, p) + size_lpmf(k | r, w);
return(ans);
}
```

which in turn gives

```
'/tmp/Rtmpk6Sttv/model-60c0517b60e9a.stan', line 2, column 2, parsing error:
-------------------------------------------------
12: }
13: }
14: real logFunction(int k, array[4] real pars){
^
15: real r = pars[1];
16: real w = pars[2];
-------------------------------------------------
"[" (list of commas) "]" expected in unsized return type of function definition.
```

What exactly is a “list of commas”? Nevermind, let’s list out the commas manually then, I suppose:

```
real logFunction(int k, array[,,,] real pars){
real r = pars[1];
real w = pars[2];
real p = pars[3];
real s = pars[4];
real ans = lbin(s, k, p) + size_lpmf(k | r, w);
return(ans);
}
```

and now

```
'/tmp/Rtmpk6Sttv/model-60c052a33c004.stan', line 2, column 2:
-------------------------------------------------
13: }
14: real logFunction(int k, array[,,,] real pars){
15: real r = pars[1];
^
16: real w = pars[2];
17: real p = pars[3];
-------------------------------------------------
Ill-typed arguments supplied to assignment operator =: lhs has type real and rhs has type array[,,] real
```

How do I get the right specification here? Consulting the reference did very little for me, I’m afraid to say.

I’m confused as to (i) what is going on and (ii) where to look for guidance. I apologise if this is a silly question, but I’ve been coding in Stan for a long while and never had this much difficulty getting something this simple to work.