added assertions

creatur.cabal

@@ -1,5 +1,5 @@
 Name:              creatur
-Version:           5.9.12
+Version:           5.9.13
 Stability:         experimental
 Synopsis:          Framework for artificial life experiments.
 Description:       A software framework for automating experiments
@@ -29,15 +29,6 @@ Maintainer:        [email protected]
 Build-Type:        Simple
 Cabal-Version:     >=1.8
 
-source-repository head
-  type:     git
-  location: https://github.com/mhwombat/creatur.git
-
-source-repository this
-  type:     git
-  location: https://github.com/mhwombat/creatur.git
-  tag:      5.9.10
-
 library
   GHC-Options:      -Wall -fno-warn-orphans
   Hs-source-dirs:   src

src/ALife/Creatur/Genetics/Recombination.hs

@@ -29,6 +29,7 @@ module ALife.Creatur.Genetics.Recombination
 import ALife.Creatur.Util (safeReplaceElement)
 
 import System.Random (Random)
+import Control.Exception.Base (assert)
 import Control.Monad.Random (Rand, RandomGen, getRandom, getRandomR)
 
 -- | Cuts two lists at the specified locations, swaps the ends, and 
@@ -166,7 +167,7 @@ randomOneOfList xs = do
 -- | Choose an element at random from a list and return the element and its 
 --   index
 randomListSelection :: RandomGen g => [a] -> Rand g (Int, a)
-randomListSelection xs = do
+randomListSelection xs = assert (not . null $ xs) $ do
   i <- getRandomR (0,length xs - 1)
   return (i, xs !! i)