| bufio | Package bufio implements buffered I/O. It wraps an io.Reader or io.Writer object, creating another object (Reader or Writer) that also implements the interface but provides buffering and some help for textual I/O. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| go/token | Package token defines constants representing the lexical tokens of the Go programming language and basic operations on tokens (printing, predicates). |
| go/types | Package types declares the data types and implements the algorithms for type-checking of Go packages. |
| internal/exportdata | Package exportdata implements common utilities for finding and reading gc-generated object files. |
| internal/godebug | Package godebug makes the settings in the $GODEBUG environment variable available to other packages. |
| internal/pkgbits | Package pkgbits implements low-level coding abstractions for Unified IR's export data format. |
| io | Package io provides basic interfaces to I/O primitives. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| slices | Package slices defines various functions useful with slices of any type. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |