Stuck in an infinite loop in a function

Question

I'm stuck in an infinite loop in this function:

let rec showGoatDoorSupport(userChoice, otherGuess, aGame) =                                       
    if( (userChoice != otherGuess) && (List.nth aGame otherGuess == "goat") ) then otherGuess
    else showGoatDoorSupport(userChoice, (Random.int 3), aGame);;

And here's how I'm calling the function:

showGoatDoorSupport(1, 2, ["goat"; "goat"; "car"]);

In the first condition in the function, I compare the first 2 input parameters (1 and 2) if the are different, and if the item in the list at index "otherGuess" is not equal to "goat", I want to return that otherGuess.

Otherwise, I want to run the function again with a random number between 0-2 as the second input parameter.

The point is to keep trying to run the function until the second parameter doesnt equal the first, and that slot in the List isn't "goat", then return that slot number.

looks like c programming habits

Joseph Elcid
– Joseph Elcid

2012-09-29 07:24:03 +00:00
Commented Sep 29, 2012 at 7:24 — Joseph Elcid
– Joseph Elcid, Commented Sep 29, 2012 at 7:24

Jeffrey Scofield · Accepted Answer · 2012-09-27 23:23:05Z

8

Don't use ==, it checks for physical equality. Use =. Two different strings will never be physically equal, even if they contain the same sequence of characters. (This is necessary, because strings are mutable in OCaml.)

$ ocaml
        OCaml version 4.00.0

# "abc" == "abc";;
- : bool = false
# "abc" = "abc";;
- : bool = true

answered Sep 27, 2012 at 23:23

Jeffrey Scofield

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3 Comments

Joshua Soileau Over a year ago

Awesome : ) You are an Ocaml master!

Jeffrey Scofield Over a year ago

Thanks, though really I'm just a humble practitioner. Ὁ βίος βραχύς, ἡ δὲ τέχνη μακρή -- Life is short, the craft is long.

gasche Over a year ago

Along the exact same line, != should not be used here, the structural difference operator is <> -- though it doesn't make much of a difference on integers.

Joseph Elcid · Accepted Answer · 2012-10-01 13:32:05Z

1

Another to do that is to use the String.compare. An example:

 if String.compare str1 str2 = 0 then (* case equal *)
 else (* case not equal *)

edited Oct 1, 2012 at 13:32

answered Sep 29, 2012 at 7:12

Joseph Elcid

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1 Comment

ygrek Over a year ago

there is no such function in stdlib, you probably meant String.compare

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