R7RSsmall

R7RSsmall is the small, or compact, portion of the R7RS Scheme standard. Published as part of the R7RS specification in the early 2010s by the Scheme Language Steering Committee, it defines a minimal yet practical baseline for Scheme implementations. The aim is to provide a portable core language with a modest standard library, balancing compatibility with existing Scheme code and ease of implementation for developers and runtimes.

Scope and features: R7RS-small covers the essential elements of the Scheme language, including core expressions, data types, and the basic evaluation rules needed to write portable programs. It provides a compact standard library that supplies commonly used procedures for lists, numbers, strings, I/O, and basic system interaction. The design favors a lightweight, interoperable core and explicitly limits the breadth of built-in features compared with the larger specification. The standard also anticipates extension through optional libraries and SRFIs, allowing implementations to provide additional functionality without expanding the core requirement.

Relationship to R7RS-large: R7RS-small serves as the baseline portion of the broader R7RS effort. The companion R7RS-large expands the language with a much larger library, broader facilities, and more extensive features, including a more expansive module and library system. In practice, many Scheme implementations aim to support R7RS-small as a minimum baseline, while others opt for R7RS-large or mix in selective SRFIs based on their goals and targets.

Adoption and influence: R7RS-small has influenced the direction of portable Scheme code by providing a commonly recognizable minimal standard. Its reception has been mixed, with some practitioners valuing its simplicity and portability, and others preferring alternative standards or dialects for broader feature sets.