The Typed Scheme Language Level

In addition to providing a language to be used with PLT Scheme modules, Typed Scheme is also available as a language selection within DrScheme. To enable this language, simply choose it in the “Choose Language” dialog found in the “Language” menu of DrScheme. Typed Scheme programs can then be entered in the definitions window, and executed with the run button.

Unlike some other languages available in DrScheme, the Typed Scheme language level does not simulate a top-level read-eval-print loop. Therefore, only one definition of a variable is allowed and uses of unbound variables result in errors.