R7RS

R7RS, short for Revised Seventh Report on the Algorithmic Language Scheme, is the seventh revision of the Scheme language standard. It was published by the Scheme community to define a portable, implementable specification of Scheme and to succeed R6RS.

The standard is presented in two parts: R7RS-small and R7RS-large. R7RS-small defines a compact, portable core of the language along with a minimal standard library intended to be easy to implement across diverse platforms. R7RS-large is an optional, more expansive library specification intended for implementations that wish to provide a rich collection of facilities beyond the core.

The small part covers the core language features, including first-class procedures and lexical scoping, as well as the fundamental data types and control structures expected of Scheme; it also prescribes a basic interface for input/output and environment management.

The large part, where implemented, furnishes a broad set of libraries and facilities such as lists, strings, I/O, networking, and other commonly required tools, but participation is optional for compliance with R7RS-small.

Adoption and impact: R7RS-small attained broad support among major Scheme implementations as a portable baseline. The large portion remains optional and has seen partial or project-specific adoption rather than unified standardization.

The two-part structure reflects an ongoing attempt to balance portability with extensibility in the Scheme ecosystem. See also: R5RS, R6RS, Scheme.