| Prompt is neither a variable nor an atom | type_error(atom, Pred) | |
| Prompt is a variable | instantiation_error | |
| Prompt is neither a variable nor an atom | type_error(atom, Pred) | |
| Word is a variable | instantiation_error | |
| Word is neither a variable nor an atom | type_error(atom, Word) | |
| Prefix is a variable | instantiation_error | |
| Prefix is neither a variable nor an atom | type_error(atom, Prefix) | |
| Word is neither a variable nor an atom | type_error(atom, Word) | |