Sagittarius is a Scheme script engine; it reads Scheme programs,
compiles it on-the-fly and executes it on a virtual machine.
Sagittarius conforms the language standard "Revised^6 Report on
the Algorithmic Language Scheme" (R6RS), "Revised^7 Report on the
Algorithmic Language Scheme" (R7RS), and supports various common
libraries defined in "Scheme Requests for Implementation" (SRFI)s.

There are a lot of Scheme implementations and they have different
strong and weak points. Sagittarius focuses on "Flexibility" and
"Easy to Use".