Runtime

Go Map Iteration Order Is Not Stable

A range over a Go map can visit the same entries in a different order on consecutive iterations. The language specification leaves map iteration order unspecified and gives no guarantee that a later pass over an unchanged map will repeat an earlier sequence. That contract is stronger than saying that maps are merely unsorted. An unsorted container could still expose a stable insertion-dependent or storage-dependent sequence. A Go program cannot assign such meaning to map traversal.