Some tips about slices

nil slices are slices

Unlink maps, slices can be used without having been allocated:

• a nil slice has a len and a cap of 0,
• you can append to a nil slice, Go will allocate it,
• you can iterate on a nil slice.

As a consequence, no need to initialize slice values of new keys in maps.

can be replaced by

resliced slices share the same underlying array

A slice is a pointer to an array. Reslicing (i.e. doing s2 := s1[a:b]) creates a new pointer to the same array, with a different starting offset and length.

As a consequence, append will modify both slices…

… unless a new array has been allocated