What is so special about constants in Go?

Constants in Go are special.

• Untyped constants. Any constant in golang, named or unnamed, is untyped unless given a type explicitly. For example an untyped floating-point constant like 4.5 can be used anywhere a floating-point value is allowed. We can use untyped constants to temporarily escape from Go’s strong type system until their evaluation in a type-demanding expression.

1       // untyped integer constant
const a = 1
var myFloat32 float32 = 4.5
var myComplex64 complex64 = 4.5

• Typed constants. Constants are typed when you explicitly specify the type in the declaration. With typed constants, you lose all the flexibility that comes with untyped constants like assigning them to any variable of compatible type or mixing them in mathematical operations.

const typedInt int = 1  

Generally we should declare a type for a constant only if it’s absolutely necessary. Otherwise, just declare constants without a type.