Allowed key and value types for a map in Go (Golang)

Maps are golang builtin datatype similar to the hash table which maps a key to a value. . Below is the format for a map:

map[key_type]value_type

Both key_type and value_type can be of different type or same type. For below example the key type is string and value type is int

map[string]int

Allowed Key types in a Map

The map key can be any type that is comparable. Some of the comparable types as defined by go specification are

• boolean
• numeric
• string,
• pointer
• channel
• interface types
• structs – if all it’s field type is comparable
• array – if the type of value of array element is comparable

Some of the types which are not comparable as per go specification and which cannot be used as a key in a map are.

• Slice
• Map
• Function

Reference – https://golang.org/ref/spec#Comparison_operators

Allowed Value types in a Map

Value can be of any type in a map.