Organise my mutual recursive types

Question

Is it possible to have mutual recursive types ([<Struct>]) spread across different files? The types are directly under a namespace.

My solution is to put them in one big file and use type ... and ... and ... etc construction. Is it the only way?

Destroy

Answer 1

You can use a technique called untying the recursive knot where you parameterize one over the other.

So this:

type a = B of b
and b = A of a

becomes:

type 'b a = B of 'b
type b = A of b a

Mug

Thanks for the answer. Is this kind of technique often used? I feel that F# design guidelines recommand to put all in one big file, right? – Destroy

I certainly use it often and recommend to our clients that they use it often but, yes, it does seem to be underappreciated. – Mug

untying the recursive knot is very useful when you try to memoize functions. It has been described in the When we need substitution of typeocaml.com/2015/01/20/mutable – Mozellemozes