Implicit phasing for R6RS libraries

Abstract

The forthcoming Revised 6 Report on Scheme differs from previous reports in that the language it describes is structured as a set of libraries. It also provides a syntax for defining new portable libraries. The same library may export both procedure and hygienic macro definitions, which allows procedures and syntax to be freely intermixed, hidden, and exported.This paper describes the design and implementation of a portable version of R 6 RS libraries that expands libraries into a core language compatible with existing R 5 RS implementations. Our implementation is characterized by its use of inference to determine when the bindings of an imported library are needed, e.g., run time or compile time, relieving programmers of the burden of declaring usage requirements explicitly.