Allow eating edible items

Add menu support to the prompt system, and an "Eat" command that prompts
for an item to eat and eats the item the character specifies, restoring
an amount of hitpoints configurable via the item raw type.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/Xanthous/Util.hs b/src/Xanthous/Util.hs
index d90cf5b03d..3a7c10ace1 100644
--- a/src/Xanthous/Util.hs
+++ b/src/Xanthous/Util.hs
@@ -24,6 +24,7 @@ module Xanthous.Util
   , uniq
     -- ** Bag sequence algorithms
   , takeWhileInclusive
+  , smallestNotIn
   ) where
 
 import Xanthous.Prelude hiding (foldr)
@@ -194,3 +195,12 @@ uniq = uniqOf folded
 takeWhileInclusive :: (a -> Bool) -> [a] -> [a]
 takeWhileInclusive _ [] = []
 takeWhileInclusive p (x:xs) = x : if p x then takeWhileInclusive p xs else []
+
+-- | Returns the smallest value not in a list
+smallestNotIn :: (Ord a, Bounded a, Enum a) => [a] -> a
+smallestNotIn xs = case uniq $ sort xs of
+  [] -> minBound
+  xs'@(x : _)
+    | x > minBound -> minBound
+    | otherwise
+    -> snd . headEx . filter (uncurry (/=)) $ zip (xs' ++ [minBound]) [minBound..]