yes it is based on SRFI-105 as explained in section 7: Features.
The project is based on R6RS (R5RS too) and SRFI for compatibility.
Linus we had a discussion about bindings month ago and Scheme+ take in account the impossibility in Scheme to have a single operator for defining a variable anywhere .
There is no more mutation in Scheme+ than in other code. If you code already use mutation with set! array-set! then Scheme+ encapsulate it with new and easy operator,that's all.
Scheme+ is 100% compatible with R6RS and SRFI.
I used it to convert a big code (see section 20:Scheme+ in action) and it worked at the first time.
let/ec, which i did not knew, is not standardised but i will work on this,thank you for your advice.
Scheme+ is really fast because macro are generally one step expanded ,or have recusivity depth of the size of the object (example array dim 3 , we recall three time the macro expansion) and on a compiled Scheme as Guile i'm not sure it is slower.(I could have done better as SRFI arrays which define a macro for each dimension 1,2,3,.... until a fixed number)
If someone have counter example with call/cc or threads making fail Scheme+ i will do my best to fix that and improve it. This is only version 1.0.
Damien