Using SWI-Prolog (threaded, 64 bits, version 8.5.0-49-g2f46def0c) on Windows.

For functor/3, trying to use with functor of `,`

.

```
?- functor(T,',',2).
T = (_, _).
```

was expecting something like

```
T = ','(_, _).
```

**EDIT**

It seems to be more of printing issue than a conversion issue,

e.g. this conversation works as expected but does not print the term `T`

as expected.

```
?- functor(T,',',2),functor(T,Funcotr,Arity).
T = (_, _),
Funcotr = (','),
Arity = 2.
```

This also works as expected.

```
?- functor(','(_,_),Functor,Arity).
Functor = (','),
Arity = 2.
```