diff options
| -rw-r--r-- | Thue/Interpreter.hs | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/Thue/Interpreter.hs b/Thue/Interpreter.hs index 896ec8a..c53bff9 100644 --- a/Thue/Interpreter.hs +++ b/Thue/Interpreter.hs @@ -26,7 +26,8 @@ thue program = interpret :: ThueState -> [ThueRule] -> StdGen -> IO ThueState interpret state rules gen = do let possibleRules = rules `applicableTo` state - ruleToApply = possibleRules !! num + ruleToApply = if (possibleRules == []) then (ThueRule "" "") else possibleRules !! num + -- ^ dummy rule if no possible rules apply (num, gen') = nextInRange 0 (length possibleRules - 1) gen |