Editor's introduction to this fascicle

This section will not appear in the final report.

The Revised7Report on the Algorithmic Language Scheme, Large Edition, is released in fascicles, which are incrementalreleases of the full standard.

This is the Procedural Fascicle(fascicle 2 of 8) containing the description of the basic syntax and procedures used for procedural programming in Scheme.It defines

  • the syntax of creating procedures (lambda),

  • the definition form for REPLs and for libraries(define),

  • forms for block-structured variable binding (let),

  • destructive assignment (set!),

  • conditional forms (if, and,or),

  • loops (named let, do),

  • and the equivalence of procedure objects.

Changes to the R7RS

The major features of this fascicle:

  • definewith no left-hand side, like in the R6RS.

  • Higher order procedure definitions like in SRFI 219

  • define-alias to make one identifier refer to another.

  • letrec-values and letrec*-values.

  • A rec form similar to the one defined in the RRRS to define anonymous recursive functions.

  • The ability to mix definitions and expressions in bodies.

  • A condthat handles multiple values as in SRFI 61.

  • The clauses for cond, case, along with the formswhen and unless, are now bodies that allow for definitions.

  • It is now syntactically valid for cond and caseto have no clauses.