Scheme Languages

From the introduction of (R5RS):

Scheme is a statically scoped and properly tail-recursive dialect of the Lisp programming language [...] designed to have an exceptionally clear and simple semantics and few different ways to form expressions. A wide variety of programming paradigms, including imperative, functional, and message passing styles, find convenient expression in Scheme.

DrScheme supports many dialects of Scheme. Five of the dialects are specifically designed for teaching computer science:

Beginning Student is a pedagogical version of Scheme that is tailored for beginning computer science students.
Beginning Student with List Abbreviations extends Beginning Student with convenient (but potentially confusing) ways to write lists, including quasiquote.
Intermediate Student adds local bindings and higher-order functions.
Intermediate Student with Lambda adds anonymous functions.
Advanced Student adds mutable state.

Other dialects are designed for practicing programmers:

R5RS is a standard dialect of Scheme that is defined by .
PLT is a superset of R5RS Scheme. In addition to the the base Scheme language, PLT Scheme provides exceptions, threads, objects, modules, components, regular expressions, TCP support, filesystem utilities, and process control operations. PLT Scheme is defined in .
More precisely, PLT exists in two flavors: textual (a.k.a. MzScheme) and graphical (a.k.a. MrEd). The graphical flavor is described in .
module supports development using PLT Scheme's form, where the module's language is explicitly declared in the code.

See for further details on the languages, especially the teaching languages.

DrScheme's set of languages can be extended, so the above list is potentially incomplete. However, documentation for all languages is available through the manuals page.

DrScheme's default language is Beginning Student. To change the language, select the Set Language... item in the Language menu.