Go Data Idioms

Slices are (ptr, len, cap) headers over a shared backing array; aliasing is the default. defer evaluates args at the defer site, not at return. Design types so the zero value is usable.

new vs make

new([]int) yields *[]int pointing to a nil slice — rarely useful. Use make([]int, n).

Slices: aliasing and append

s := []int{1, 2, 3, 4}
t := s[1:3]            // shares backing; t[0]=9 mutates s[1]
u := append(s, 5)      // may or may not reallocate