This is a very brief summary of what's changed in WG1 relative to R5RS so far. It is emphatically not authoritative, just a quick thing to point people to who haven't been following the process and aren't up for reading through whole drafts. I may have left out some tickets.
- Modules with import, export, begin (for embedded code), include, include-ci, and cond-expand
- Syntax-rules: ellipsis escaping, SRFI 46, tail patterns, and the _ wildcard
- Identifiers are case-sensitive
- Identifiers and other syntax must be delimited with whitespace
- Extended identifier syntax, including \ and |...| escapes
- #; and #| ... |# comment styles
- List of named characters and string esscapes standardized
- Exception system
- The only standardized condition is error (with accessors and predicate)
- Inexact infinities on systems that support them
- IEEE semantics for transcendental functions
- Unicode is supported but not required, including folding and normalization
- Binary I/O
- String and bytevector ports
- SRFI 9 records
- Transcript-on and transcript-off are gone
- Letrec*, let-values, and let*-values
- Syntax-error
- Map, for-each, assoc, and member extended as in SRFI 1
- Internal define-syntax
- Bytevectors
- Support for cyclic list structure as in SRFI 1
- Read and write cyclic data, with write-simple to suppress writing
- exact-integer? and exact-integer-sqrt
- Current-error-port
- Delete-file and file-exists
- Finite? and nan? as in R6RS but supporting complex numbers too
- Command-line, exit, get-environment-variable, get-environment-variables
- Call/cc
- SRFI 39 parameters
- Access to TAI and elapsed time
- Case-lambda
- => in case
- Case folding flags
- DivisionRiastradh
- Port?, close-port, and port-closed?
- Real numbers have #e0 as the imaginary part
- Nested quasiquotes with partial specification for mutability
- Procedures need not be tagged with locations
- Dynamic-wind thunks run in the outer dynamic environment
- Read-line
- Physical newline in a string means \n
- Environment from R6RS
- Multiple values can be sent to continuations which discard them