This page summarizes the changes between tagged releases of Go. For full details, see the Mercurial change log.
++This release contains three language changes: + +1. Accessing a non-existent key in a map is no longer a run-time error. +It now evaluates to the zero value for that type. For example: + x := myMap[i] is now equivalent to: x, _ := myMap[i] + +2. It is now legal to take the address of a function's return value. +The return values are copied back to the caller only after deferred +functions have run. + +3. The functions panic and recover, intended for reporting and recovering from +failure, have been added to the spec: + http://golang.org/doc/go_spec.html#Handling_panics +In a related change, panicln is gone, and panic is now a single-argument +function. Panic and recover are recognized by the gc compilers but the new +behavior is not yet implemented. + +The ARM build is broken in this release; ARM users should stay at release.2010-03-22. + +Other changes: +* bytes, strings: add IndexAny. +* cc/ld: Add support for #pragma dynexport, + Rename dynld to dynimport throughout. Cgo users will need to rerun cgo. +* expvar: default publishings for cmdline, memstats +* flag: add user-defined flag types. +* gc: usual bug fixes +* go/ast: generalized ast filtering. +* go/printer: avoid reflect in print. +* godefs: fix handling of negative constants. +* godoc: export pprof debug information, exported variables, + support for filtering of command-line output in -src mode, + use http GET for remote search instead of rpc. +* gofmt: don't convert multi-line functions into one-liners, + preserve newlines in multiline selector expressions (thanks Risto Jaakko Saarelma). +* goinstall: include command name in error reporting (thanks Andrey Mirtchovski) +* http: add HandleFunc as shortcut to Handle(path, HandlerFunc(func)) +* make: use actual dependency for install +* math: add J1, Y1, Jn, Yn, J0, Y0 (Bessel functions) (thanks Charles L. Dorian) +* prof: add pprof from google-perftools +* regexp: don't return non-nil *Regexp if there is an error. +* runtime: add Callers, + add malloc sampling, pprof interface, + add memory profiling, more statistics to runtime.MemStats, + implement missing destroylock() (thanks Alex Brainman), + more malloc statistics, + run all finalizers in a single goroutine, + Goexit runs deferred calls. +* strconv: add Atob and Btoa, + Unquote could wrongly return a nil error on error (thanks Roger Peppe). +* syscall: add IPV6 constants, + add syscall_bsd.go for Darwin and other *BSDs (thanks Giles Lean), + implement SetsockoptString (thanks Christopher Wedgwood). +* websocket: implement new protocol (thanks Fumitoshi Ukai). +* xgb: fix request length and request size (thanks Firmansyah Adiputra). +* xml: add CopyToken (thanks Kyle Consalus), + add line numbers to syntax errors (thanks Kyle Consalus), + use io.ReadByter in place of local readByter (thanks Raif S. Naffah). ++