Mapping outline

gistfile1.ml

type c = {x : int; y: int ; z : int ;}
let c_empty ?(x=1) ?(y=1) ?(z=1) () = { x; y; z }

let my_func (foos:int) = [ [ c_empty () ] ]

myData 
|> my_func
|> ....

type d = {t : int; u : int; v : int;}
type e = {w : d} 

let d_empty ?(t=0) ?(u=0) ?(v=0) () = {t; u; v}
let e_empty ?(w=(d_empty ())) () = {w}