| 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/scanner | Package scanner implements a scanner for Go source text. |
| 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. |
| golang.org/x/tools/go/callgraph | Package callgraph defines the call graph and various algorithms and utilities to operate on it. |
| 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. |
| golang.org/x/tools/go/pointer | Package pointer implements Andersen's analysis, an inclusion-based pointer analysis algorithm first described in (Andersen, 1994). |
| golang.org/x/tools/go/ssa | Package ssa defines a representation of the elements of Go programs (packages, types, functions, variables and constants) using a static single-assignment (SSA) form intermediate representation (IR) for the bodies of functions. |
| golang.org/x/tools/go/ssa/ssautil | |
| golang.org/x/tools/go/types/typeutil | Package typeutil defines various utilities for types, such as Map, a hash table that maps types.Type to any value. |
| html | Package html provides functions for escaping and unescaping HTML text. |
| io | Package io provides basic interfaces to I/O primitives. |
| log | Package log implements a simple logging package. |
| math/big | Package big implements arbitrary-precision arithmetic (big numbers). |
| os | Package os provides a platform-independent interface to operating system functionality. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| reflect | Package reflect implements run-time reflection, allowing a program to manipulate objects with arbitrary types. |
| sort | Package sort provides primitives for sorting slices and user-defined collections. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |