| 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. |
| bytes | Package bytes implements functions for the manipulation of byte slices. |
| encoding/json | Package json implements encoding and decoding of JSON as defined in RFC 7159. |
| flag | Package flag implements command-line flag parsing. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| go/ast | Package ast declares the types used to represent syntax trees for Go packages. |
| go/build | Package build gathers information about Go packages. |
| go/constant | Package constant implements Values representing untyped Go constants and their corresponding operations. |
| go/format | Package format implements standard formatting of Go source. |
| go/parser | Package parser implements a parser for Go source files. |
| go/types | Package types declares the data types and implements the algorithms for type-checking of Go packages. |
| golang.org/x/text/language | Package language implements BCP 47 language tags and related functionality. |
| golang.org/x/tools/go/buildutil | Package buildutil provides utilities related to the go/build package in the standard library. |
| golang.org/x/tools/go/loader | Package loader loads a complete Go program from source code, parsing and type-checking the initial packages plus their transitive closure of dependencies. |
| io | Package io provides basic interfaces to I/O primitives. |
| io/ioutil | Package ioutil implements some I/O utility functions. |
| log | Package log implements a simple logging package. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| path | Package path implements utility routines for manipulating slash-separated paths. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| text/template | Package template implements data-driven templates for generating textual output. |
| unicode | Package unicode provides data and functions to test some properties of Unicode code points. |
| unicode/utf8 | Package utf8 implements functions and constants to support text encoded in UTF-8. |