A type error occurs when an input argument is of the wrong type. In general,
a type is taken to be a class of terms for which there exists a unary type
test predicate. Some types are built-in, such as
The type of a term is the sort of thing you can tell just by looking at it, without checking to see how big it is. So “integer” is a type, but “non-negative integer” is not, and “atom” is a type, but “atom with 5 letters in its name” and “atom starting with ‘x’” are not.
The point of a type error is that you have obviously passed the wrong sort of argument to a command; perhaps you have switched two arguments, or perhaps you have called the wrong predicate, but it isn’t a subtle matter of being off by one.
Most built-in predicates check all their input arguments for type errors.
The SICStus_Error term associated with a type error is
type_error(Goal, ArgNo, TypeName, Culprit)
Culprit occurs somewhere in the ArgNoth argument of Goal.
says what sort of term was expected; it should be the name of a unary predicate that is true of whatever terms would not provoke a type error.
is the actual term being complained about: TypeName(Culprit) should be false.
| ?- catch((write(3),1), Error, true). Error = error(type_error(callable,(write(3),1)), type_error(user:(write(3),1),0,callable,(write(3),1)))