A partial implementation of r7rs-pico (previously named r7rs-tiny)
This was created as part of r7rs-pico for testing various parts of the semantics.
Major differences between r7rs-pico is this is not properly tail recursive (tail recursion uses heap space), and there are various differences in the syntax.
Integers are 64 bit signed integers, and overflow of +,-,* will return #f
Integer constants that are too big will be renamed to invalid_number_ followed by the number.
The r7rs-pico specification is at: https://github.com/jrincayc/r7rs-pico-spec