What is an idiomatic way of representing enums in Go?

Question

I'm trying to represent a simplified chromosome, which consists of N bases, each of which can only be one of {A, C, T, G}.

I'd like to formalize the constraints with an enum, but I'm wondering what the most idiomatic way of emulating an enum is in Go.

Answer 1

Quoting from the language specs:Iota

Within a constant declaration, the predeclared identifier iota represents successive untyped integer constants. It is reset to 0 whenever the reserved word const appears in the source and increments after each ConstSpec. It can be used to construct a set of related constants:

const (  // iota is reset to 0         c0 = iota  // c0 == 0         c1 = iota  // c1 == 1         c2 = iota  // c2 == 2 )  const (         a = 1 << iota  // a == 1 (iota has been reset)         b = 1 << iota  // b == 2         c = 1 << iota  // c == 4 )  const (         u         = iota * 42  // u == 0     (untyped integer constant)         v float64 = iota * 42  // v == 42.0  (float64 constant)         w         = iota * 42  // w == 84    (untyped integer constant) )  const x = iota  // x == 0 (iota has been reset) const y = iota  // y == 0 (iota has been reset) 

Within an ExpressionList, the value of each iota is the same because it is only incremented after each ConstSpec:

const (         bit0, mask0 = 1 << iota, 1<<iota - 1  // bit0 == 1, mask0 == 0         bit1, mask1                           // bit1 == 2, mask1 == 1         _, _                                  // skips iota == 2         bit3, mask3                           // bit3 == 8, mask3 == 7 ) 

This last example exploits the implicit repetition of the last non-empty expression list.

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So your code might be like

const (         A = iota         C         T         G ) 

or

type Base int  const (         A Base = iota         C         T         G ) 

if you want bases to be a separate type from int.