Algol 68 Type System

The type system of ALGOL 68 has been adopted, more or less faithfully, in many subsequent languages. In particular, the structs, the unions, the pointer types, and the parameter passing of C were influenced by ALGOL 68 [Ritchie 1993], although the syntactic sugar is bizarre and C is not so strongly typed. Another language with a related type system is SML [Milner 1990], particularly with regard to its use of ref types as its means of realizing variables, and C++ has also benefitted from the ref types [Stroustrup 1996]. Even the Intuitionistic Theory of Types [Lof 1984] uses essentially the same type system.
http://cs305.com/book/programming_languages/Conf-01/HOPLII/p27-lindsey.pdf