Memory Layout of Go Types

Go stores structs as contiguous blocks of fields, slices as headers pointing to heap arrays, maps as pointers to hash tables, and interfaces as pairs of type and data pointers. Structs live inline or on the heap, while slices, maps, and interfaces always allocate their data on the heap.

// Struct: fields are contiguous
s := struct{ A int; B string }{A: 1, B: "hi"}

// Slice: header (ptr, len, cap) points to heap array
sl := []int{1, 2, 3}

// Map: pointer to hash table on heap
m := map[string]int{"a": 1}

// Interface: (type, data) pair
var i interface{} = "hello"

Go types live in memory differently to balance speed and flexibility. Structs pack data together tightly, while slices, maps, and interfaces act like pointers that reference larger data blocks stored elsewhere. Think of a struct as a packed suitcase, while a slice or map is a receipt pointing to a storage unit where the actual items are kept.