make / new / len / cap
s := make([]int, 3, 8) // len 3, cap 8
m := make(map[string]int, 16)
p := new(int) // *int pointing to zero value
len(s); cap(s); len(m)builtin
Documentation-only package for the predeclared identifiers (len, cap, append, make, new, delete, panic, recover, any, error, ...). Always in scope.
Slices and maps
append / copy / clear / delete
s = append(s, 4, 5)
n := copy(dst, src)
clear(s) // Go 1.21+: zero all elements
clear(m) // empty map
delete(m, "key")Channels and control flow
close / panic / recover
close(ch)
panic("boom")
defer func() { if r := recover(); r != nil { /* handled */ } }()Numeric helpers
min / max (Go 1.21+)
min(3, 1, 2) // 1
max(3.0, 1.0) // 3.0Predeclared types
Aliases
any // alias for interface{}
error // interface{ Error() string }
byte // alias for uint8
rune // alias for int32
comparable // type constraint