Type-checking in an untyped language

✍ Scribed by Allan Ramsay

• Book ID: 104139877
• Publisher: Elsevier Science
• Year: 1984
• Weight: 620 KB
• Volume: 20
• Category: Article
• ISSN: 0020-7373
• DOI: 10.1016/s0020-7373(84)80015-2

✦ Synopsis

It is argued that typed variables and functions are inappropriate for languages which allow functional arguments, data types defined by predicates, and conditional expressions that test data types. However, it is still possible to do some compile-time type-checking for such languages. This paper presents a technique for inferring data types in an untyped language, and a program that uses this technique to show where type constraints are obeyed or violated and where run time checks are needed. This operation must check that the stack is not empty--if it is the system informs the user that there has been an error. call (item) checks that the item is a function, informing the user that there is an error if it is not. If it is, call saves the current "stack frame" (i.e. all the information