Group Type Testing
Coalesce()
Returns the first non NIL/NULL expression among its arguments.
Coalesce( <Expression,...> ) --> <Expression>
CoalesceEmpty()
Returns the first non empty expression among its arguments.
CoalesceEmpty( <Expression,...> ) --> <Expression>
Empty()
Tests whether an expression returns an empty value.
Empty( <Expression> ) --> lEmpty
IsNull()
Tests if an expression evaluates to NULL/NIL.
IsNull( <Expression> ) --> lIsNull IsNull( <Expression>, <ReplacementValue> ) --> xValue
Type()
Determines the data type of an expression.
Type( <cExpression> ) --> cType
Valtype()
Determines the data type of a value.
Valtype( <Expression> ) --> cType