Question

在下面的代码中，行val () = println! ("-> ", nn)会生成错误：

$ myatscc collatz.dats
/home/brandon/workspace/ATStest/collatz/collatz.dats: 203(line=13, offs=13) -- 225(line=13, offs=35): error(3): the symbo
l [print] cannot be resolved due to too many matches:
D2ITMcst(print_option) of 0
D2ITMcst(print_list_vt) of 0
/home/brandon/workspace/ATStest/collatz/collatz.dats: 203(line=13, offs=13) -- 225(line=13, offs=35): error(3): the dynam
ic expression cannot be assigned the type [S2Ecst(atsvoid_t0ype)].
/home/brandon/workspace/ATStest/collatz/collatz.dats: 203(line=13, offs=13) -- 225(line=13, offs=35): error(3): mismatch
of static terms (tyleq):
The actual term is: S2Eerrexp()
The needed term is: S2Ecst(atsvoid_t0ype)
patsopt(TRANS3): there are [2] errors in total.
exit(ATS): uncaught exception: _2home_2brandon_2workspace_2ATS_2dPostiats_2src_2pats_error_2esats__FatalErrorExn(1025)

这是代码

(*
 To compile:
 myatscc collatz.dats
*)

#include "share/atspre_staload.hats"

//TODO: add guards to make sure nn is non-negative
fun collatz(nn: int): int = let
  val newN: int =
    if nn % 2 = 0 then nn / 2
    else 3 * nn + 1 
  //FIXME: too many matches: print_option or print_list_vt:
  // val () =  println! ("-> ", nn)  
  //FIXME: Why is this not printing:
  val () =  println! ("-> ", 1)  
in 
  if (newN: int) != (1: int) then collatz(newN)
  else newN
end

implement
main0 () = {
 val _ = collatz(42)
}

我也很困惑为什么这个假的println！没有被执行（val () = println! ("-> ", 1)）。

这是Scala（run it online）中的一个程序，可以完成我的目标：

@tailrec
def collatz(n: BigInt): BigInt = {
 assert (n > 0)
 val newN = 
  if (n % 2 == 0) n / 2
  else 3 * n + 1
 println(s"-> $newN") 
 if (newN != 1) collatz(newN)
 else newN
}

collatz(BigInt("7893450809435834508"))

如何使用println！在一个int

0 个答案: