Editing Scheme (programming language) (section)

== Scheme Requests for Implementation ==
{{Main|Scheme Requests for Implementation}}
Because of Scheme's minimalism, many common procedures and syntactic forms are not defined by the standard. In order to keep the core language small but facilitate standardization of extensions, the Scheme community has a "Scheme Request for Implementation" (SRFI) process by which extension libraries are defined through careful discussion of extension proposals. This promotes code portability. Many of the SRFIs are supported by all or most Scheme implementations.

SRFIs with fairly wide support in different implementations include:<ref name="srfi_support">{{Cite web |date=2009-08-30 |title=Scheme Systems Supporting SRFIs |url=http://srfi.schemers.org/srfi-implementers.html |access-date=2012-08-09 |publisher=The SRFI Editors, schemers.org}}</ref>

* 0: feature-based conditional expansion construct
* 1: list library
* 4: homogeneous numeric vector datatypes
* 6: basic string ports
* 8: receive, binding to multiple values
* 9: defining record types
* 13: string library
* 14: character-set library
* 16: syntax for procedures of variable [[arity]]
* 17: generalized set!
* 18: Multithreading support
* 19: time data types and procedures
* 25: multi-dimensional array primitives
* 26: notation for specializing parameters without [[currying]]
* 27: sources of random bits
* 28: basic format strings
* 29: [[Internationalization and localization|localization]]
* 30: nested multi-line comments
* 31: a special form for recursive evaluation
* 37: args-fold: a program argument processor
* 39: parameter objects
* 41: [[Stream (computing)|stream]]s
* 42: [[List comprehension|eager comprehensions]]
* 43: vector library
* 45: primitives for expressing iterative lazy algorithms
* 60: integers as bits
* 61: a more general cond clause
* 66: octet vectors
* 67: compare procedures