1 files changed, 30 insertions, 3 deletions
diff --git a/src/Miscellaneous.hs b/src/Miscellaneous.hs
index 94e9672..de20a3d 100644
--- a/src/Miscellaneous.hs
+++ b/src/Miscellaneous.hs
@@ -1,7 +1,15 @@
 module Miscellaneous(
-    if'
-    (?)
-    ) where\
+    if',
+    (?),
+    selectFrom
+    ) where
+
+
+
+
+import Control.Monad as Con
+import qualified Data.List as List
+import qualified Data.Maybe as Maybe
 
 
 
@@ -17,3 +25,22 @@ infixr 1 ?
 (?) = if'
 
 
+
+--  kinda functions like poor man's sql
+--  first argument is the indices of the items you want in the results
+--  second argument is index-item pairs to dictate what records are acceptable to select from
+--  third argument is the list of items that makes up the record under consideration
+--  then if the record was deemed acceptable you get the bits you wanted
+--  (note that all indices start from 1)
+selectFrom :: (Num t, Eq t, Eq a, Enum t) => [t] -> [(t,a)] -> [a] -> Maybe [a]
+selectFrom pick has from =
+    let tailFunc r i =
+            let check = List.lookup (fst i) has
+            in if (Maybe.isNothing check || Maybe.fromJust check == snd i)
+                then if (List.elem (fst i) pick)
+                        then Just (r ++ [snd i])
+                        else Just r
+                else Nothing
+    in Con.foldM tailFunc [] (zip [1,2..] from)
+
+