The concept of first- and second-class objects was introduced by Christopher Strachey in the 1960s.[2][3] He did not actually define the term strictly, but contrasted real numbers and procedures in ALGOL:
First and second class objects. In ALGOL, a real number may appear in an expression or be assigned to a variable, and either of them may appear as an actual parameter in a procedure call. A procedure, on the other hand, may only appear in another procedure call either as the operator (the most common case) or as one of the actual parameters. There are no other expressions involving procedures or whose results are procedures. Thus in a sense procedures in ALGOL are second class citizens—they always have to appear in person and can never be represented by a variable or expression (except in the case of a formal parameter)...First and second class objects. In ALGOL, a real number may appear in an expression or be assigned to a variable, and either of them may appear as an actual parameter in a procedure call. A procedure, on the other hand, may only appear in another procedure call either as the operator (the most common case) or as one of the actual parameters. There are no other expressions involving procedures or whose results are procedures. Thus in a sense procedures in ALGOL are second class citizens—they always have to appear in person and can never be represented by a variable or expression (except in the case of a formal parameter)... [4]
Крч, объекты первого класса могут присваиваться и передаваться аргументами, а также возвращаться результатом из функций. Объекты второго класса (говоря о функциях) - соответственно, не могут как минимум одно из перечисленного. Думаю, не нужно называть языки где функции могут быть объявлены только статически и не могут присваиваться/передаваться как объектные экземпляры... А объектов "третьего и далее" классов, вроде не существует))
