Why Can't I Declare a Constant Map in Go?

Understanding Constant Maps in Go: Why Declaration and Subsequential Assignment Are Prohibited

In Go, a constant is a value that cannot be modified once declared. This characteristic is fundamental to constants, ensuring they consistently retain their defined value.

The use of maps, a data structure that stores key-value pairs, presents an exception to this principle. Maps are inherently mutable, allowing for the addition, modification, and deletion of key-value pairs even after initialization. This mutability conflicts with the immutability required of constants.

As such, Go does not permit the declaration of constant maps. Attempting to assign values to a map declared as a constant, as seen in the example provided, will result in a compilation error.

The error stems from the violation caused by modifying a constant. Maps are dynamic structures that require reallocation to accommodate changes, contradicting the requirement of constants to remain immutable.

To overcome this limitation, consider declaring the map as a variable instead of a constant, granting the ability to modify its key-value pairs after initialization.

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