Stack overflow during evaluation (looping recursion?) error

Question

function seq should return a sequence starting from init and at each time extends by step untill the condition is not verified:

let  rec seq init step cond () = 
let r = ref init in
if cond !r 
then  Cons(step !r, seq !r step cond)
else Nil

i tried these (to_list (seq 1 seq 1 (fun x -> x+1) (fun x -> x <10)) and i have Stack overflow during evaluation (looping recursion?).

comment not related to your SO : why do you use () in let rec seq init step cond () ? why not simply let rec seq init step cond ? — Pierre G.
– Pierre G., Commented Apr 24, 2018 at 9:58
if i use only like seq init step cond like you said it will return a 'a node not an 'a t — maya
– maya, Commented Apr 24, 2018 at 10:33
OK - I see, it is related to the other ticket you have posted (stackoverflow.com/questions/49636168/…) in which you define those types. — Pierre G.
– Pierre G., Commented Apr 24, 2018 at 11:25

octachron · Accepted Answer · 2018-04-24 11:30:50Z

4

First, you should avoid using reference without good reason. Then it is just a matter of storing the current value and not the next one:

let rec seq current step cond () =
if cond current then 
  Cons(current, seq (step current) step cond)
else
  Nil

answered Apr 24, 2018 at 11:30

octachron

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