$func? IsBox e.Exp = ;
$func? IsChannel e.Exp = ;
$func? IsChar e.Exp = ;
$func? IsDigit e.Exp = ;
$func? IsFunc e.Exp = ;
$func? IsInt e.Exp = ;
$func? IsLetter e.Exp = ;
$func? IsString e.Exp = ;
$func? IsTable e.Exp = ;
$func? IsVector e.Exp = ;
$func? IsWord e.Exp = ;
These functions provides a way to determine whether e.Exp is a symbol belonging to a certain class of symbol.
If e.Exp is not a single symbol, the functions return $fail(0).
If e.Exp is a symbol, the test is performed whether the symbol belongs to the corresponding class of symbols. If so, the value returned is an empty ground expression. Otherwise, the value returned is $fail(0).
The correspondence between the predicate functions and the sets of symbols is as follows.
| IsBox | - references to boxes. |
| IsChannel | - references to channels. |
| IsChar | - character symbols. |
| IsDigit | - character symbols corresponding to decimal digits. |
| IsFunc | - references to functions. |
| IsInt | - references to integers. |
| IsLetter | - character symbols corresponding to small and capital letters. |
| IsString | - references to strings. |
| IsTable | - references to tables. |
| IsVector | - references to vectors. |
| IsWord | - word symbols. |