The thing that’s remarkable is that, with iota, you can specify an expression that computes the enum value: For example, this: const ( Foo = 2 * iota //

The thing that’s remarkable is that, with iota, you can specify an expression that computes the enum value: For example, this: const ( Foo = 2 * iota // 0 Bar = 2 * iota // 2 Baz = 3 * iota // 6 // ... ) It typically is combined with another feature, explicit repetition of the last non-empty expression list (https://go.dev/ref/spec#Constant_declarations https://go.dev/ref/spec#Constant_declarations) to avoid having to repeat the iota expression. For a powerful example see https://go.dev/ref/spec#Iota https://go.dev/ref/spec#Iota: By definition, multiple uses of iota in the same ConstSpec all have the same value: const ( bit0, mask0 = 1 << iota, 1<<iota - 1 // bit0 == 1, mask0 == 0 (iota == 0) bit1, mask1 // bit1 == 2, mask1 == 1 (iota == 1) _, _ // (iota == 2, unused) bit3, mask3 // bit3 == 8, mask3 == 7 (iota == 3) ) I think that’s bordering on “too smart for it’s own good”, but it does prevent a very common copy-paste bug in C, where one would write something like enum { bit0 = 1 << 0, bit1 = 1 << 1, bit3 = 1 << 3, mask0 = bit0 - 1 mask1 = bit1 - 1, mask3 = bit1 - 1 // copy-paste error } (Happens fairly easily in real world code when the Enums are long, and extra Enums get added over time)