Best way to dispatch on whether a value is `isbits`?

There are infinitely many types for which isbits is true. But I want to make my function dispatch on whether the eltype is isbits. What’s the best way to do that?

I think of 4 approaches to do that

1.Use if

Don’t use dispatch at all; just use if-statements
Easy to understand but doesn’t use “dispatch”

2. Use Val{true|false}

fn(v) = fn(Val(isbits(eltype(v)), v) 
fn(Val{True}, v) = # do something
fn(Val{False}, v) = # do something else

3. Make a new type IsBitsType

with two subtypes which are IsBitsTrueType and IsBitsFalseType and make a series of function like in 2. to dispatch

4. Make a new type IsBitsType2 with 2 values

The two possible values are isbitstrue and isbitsfalse and the type is defined like so

struct IsBitsType2

and dispatch using similar mechanism as in 2.

It feels like 2 is what I would do, but keen to hear opinions on this. It sounds like 3 is very Julia specific way but I always get confused, e.g when I use the Algorithm type when sorting, so I think I should avoid creating sub-types just for dispatch.

That’s pretty much the standard solution:

That said, when the criterion is binary, there is nothing wrong with a branch either, eg

f(v) = isbitstype(eltype(v)) ? do_something(v) : do_something_else(v)