coq - Unknown Interpretation for "_/_" despite importing Arith -


i trying write function converts nat string in coq. here attempt.

require import arith string.  (*   append part of string library. signature                  (s1 : string) : string -> string *)  fixpoint convert_nat_to_string (n : nat) : string := match n   | 0 => string "0" emptystring    | 1 => string "1" emptystring   | 2 => string "2" emptystring   | 3 => string "3" emptystring   | 4 => string "4" emptystring   | 5 => string "5" emptystring   | 6 => string "6" emptystring   | 7 => string "7" emptystring   | 8 => string "8" emptystring   | 9 => string "9" emptystring   | _ => (append (convert_nat_to_string (n/10))) (convert_nat_to_string (n mod 10)) end.

however, on last branch, coqide gives me error

error: unknown interpretation notation "_ / _".

even though have imported arith library. know why getting error message?

proof / part of arith:

coq < require import arith. [loading ml file z_syntax_plugin.cmxs ... done] [loading ml file quote_plugin.cmxs ... done] [loading ml file newring_plugin.cmxs ... done] <w> grammar extension: in [tactic:simple_tactic], rule has been masked <w> grammar extension: in [tactic:simple_tactic], rule has been masked <w> grammar extension: in [tactic:simple_tactic], rule has been masked <w> grammar extension: in [tactic:simple_tactic], rule has been masked <w> grammar extension: in [tactic:simple_tactic], rule has been masked  coq < check 5/10. 5 / 10      : nat

as of coq 8.6, function available in coq.arith.peanonat.

require import coq.arith.peanonat.  check 10 / 5. (* --> 10 / 5 : nat *)

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