document SRFIs

1 files changed, 26 insertions, 1 deletions

diff --git a/README.md b/README.md
index 0d84980..0c6e172 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,32 @@ use the `portable-r7rs-build-system` (`portable-r6rs-build-system`).
 On systems that support both R6RS and R7RS, the R6RS libraries will
 take precedence (rationale: R6RS has more stuff).
 
-## Supported
+## SRFIs and Portability Libraries
+
+This channel packages some SRFIs for portable use. They are labeled
+`srfi-M-rNrs`, where `M` is the number and `N` is the standard. The
+SRFIs are packaged so that R7RS systems use `(srfi M)` and R6RS
+systems use `(srfi :M)`. No claim is made to the portability of
+`(srfi :M name)`, etc, unless made necessary by sublibraries.
+
+* SRFI-1
+* SRFI-8
+* SRFI-9 (R6RS only)
+* SRFI-128
+* SRFI-227
+
+None of these packages have any dependencies. This is because some
+implementations already come with optimized versions of these SRFIs. For
+instance, a system with built-in comparators doesn't need to pull in
+the portable SRFI-128 implementation to use some other library that imports
+SRFI-128.
+
+The following portability libraries are also exported.
+
+* `compatible-parameters`: Exports `(mcgoron compatible-parameters)` for
+  R6RS systems that exports either an SRFI-39 or R7RS parameter interface.
+
+## Supported Implementations
 
 ### Chibi Scheme