lab04b: init

lab04/ho.hs

@@ -0,0 +1,77 @@
+import qualified Data.Map as Map
+
+m = Map.empty
+m' = Map.insert 3 "hello" m
+s = case (Map.lookup 3 m') of
+      Just s' -> s'
+      Nothing -> error "not found"
+
+
+addNums x y = x + y
+
+inc :: Int -> Int
+inc = addNums 1
+
+incList :: [Int] -> [Int]
+incList [] = []
+incList (x:xs) = inc x : (incList xs)
+
+decList :: [Int] -> [Int]
+decList [] = []
+decList (x:xs) = (x-1) : (decList xs)
+
+
+applyFun2List :: (a->b) -> [a] -> [b]
+applyFun2List _ [] = []
+applyFun2List f (x:xs) = (f x) : (applyFun2List f xs)
+
+incList' = applyFun2List inc
+--incList' = map inc
+
+
+removeNegatives :: [Integer] -> [Integer]
+removeNegatives [] = []
+removeNegatives (x:xs) =
+  let rest = removeNegatives xs in
+    if x >= 0 then
+      x : rest
+    else
+      rest
+
+--filter
+removeBadElems :: (a -> Bool) -> [a] -> [a]
+removeBadElems _ [] = []
+removeBadElems pred (x:xs) =
+  let rest = removeBadElems pred xs in
+    if pred x then
+      x : rest
+    else
+      rest
+
+
+
+addListOfNums :: Num a => a -> [a] -> a
+addListOfNums accum [] = accum
+addListOfNums accum (x:xs) = addListOfNums (accum + x) xs
+
+decListOfNums :: Num a => a -> [a] -> a
+decListOfNums accum [] = accum
+decListOfNums accum (x:xs) = addListOfNums (accum - x) xs
+
+addListOfNumStrings :: Int -> [String] -> Int
+addListOfNumStrings accum [] = accum
+addListOfNumStrings accum (s:xs) = addListOfNumStrings (accum + (read s)) xs
+
+
+--foldl
+foldTogether :: (a -> b -> a) -> a -> [b] -> a
+foldTogether _ accum [] = accum
+foldTogether f accum (x:xs) = foldTogether f (f accum x) xs
+
+addListOfNums' :: Num a => [a] -> a
+addListOfNums' = foldTogether (+) 0
+
+
+
+
+