Avoid using partial functions from Data.List

Use Data.List.Infinite, Data.List.NonEmpty and drop instead

Analysis.hs

@@ -1,5 +1,9 @@
 module Analysis where
 
+import Prelude hiding (head, iterate)
+
+import Data.List.Infinite (Infinite ((:<)), head, iterate)
+
 data Criticality = Maximum | Minimum | Inflection
     deriving (Eq, Show, Read)
 
@@ -27,10 +31,9 @@ solve :: (Fractional t, Ord t) =>
 solve f f' e (x0, _) = head . convergedBy e . iterate step $ x0
   where step x = x - f x / f' x
 
-dropWhile2 :: (t -> t -> Bool) -> [t] -> [t]
-dropWhile2 p xs@(x : xs'@(x' : _)) = if not (p x x') then xs else dropWhile2 p xs'
-dropWhile2 _ xs = xs
+dropWhile2 :: (t -> t -> Bool) -> Infinite t -> Infinite t
+dropWhile2 p xs@(x :< xs'@(x' :< _)) = if not (p x x') then xs else dropWhile2 p xs'
 
-convergedBy :: (Num t, Ord t) => t -> [t] -> [t]
+convergedBy :: (Num t, Ord t) => t -> Infinite t -> Infinite t
 convergedBy e = dropWhile2 unconverging
   where unconverging x x' = abs (x - x') >= e

Extremes.hs

@@ -34,7 +34,7 @@ main = do
 
     let (highs, lows) = partition ((== Maximum) . exType) times
         cmp = comparing (snd . exPoint)
-        ranges = zipWith sub times $ tail times
+        ranges = zipWith sub times $ drop 1 times
         sub (Extremum (t, h) c) (Extremum (_, h') _) = Extremum (t, abs (h - h')) c
 
     forM_ (take 10 $ sortBy (flip cmp) highs) $

Tides.cabal

@@ -43,6 +43,7 @@ executable Tides
         base >=4.6.0.1 && <5,
         directory >=1.2.0.1 && <1.4,
         filepath >=1.3.0.1 && <1.5,
+        infinite-list >=0.1 && <0.2,
         mtl >=2.2.2 && <2.4,
         time >=1.5 && <1.13,
         time-locale-compat >=0.1.1.3 && <0.2,
@@ -64,6 +65,7 @@ executable Extremes
         base >=4.6.0.1 && <5,
         directory >=1.2.0.1 && <1.4,
         filepath >=1.3.0.1 && <1.5,
+        infinite-list >=0.1 && <0.2,
         time >=1.5 && <1.13,
         time-locale-compat >=0.1.1.3 && <0.2,
         tz >=0.0.0.5 && <0.2,
@@ -120,6 +122,7 @@ executable TestTides
         base >=4.6.0.1 && <5,
         directory >=1.2.0.1 && <1.4,
         filepath >=1.3.0.1 && <1.5,
+        infinite-list >=0.1 && <0.2,
         time >=1.5 && <1.13,
         time-locale-compat >=0.1.1.3 && <0.2,
         tz >=0.0.0.5 && <0.2,
@@ -213,6 +216,7 @@ test-suite TestRegressions
         filepath >=1.3.0.1 && <1.5,
         hspec >=2.7.6,
         hspec-golden >=0.1.0.3,
+        infinite-list >=0.1 && <0.2,
         mtl >=2.2.2 && <2.4,
         process >=1.2.3 && <1.7,
         random >=1.1 && <1.3,

Tides.hs

@@ -10,10 +10,11 @@ import Control.Arrow (first)
 import Control.Monad (unless, (<=<))
 import Control.Monad.IO.Class (MonadIO(..))
 import Data.Function
-import Data.List (groupBy)
 import Data.Time
 import Data.Time.Zones
 
+import qualified Data.List.NonEmpty as NE
+
 type Prediction = (ZonedTime, Double)
 type Event      = Extremum Prediction
 
@@ -36,17 +37,17 @@ tides station begin end step = do
 
     --name    <- return . tshName . trHeader $ r
     --country <- getCountry . trCountry $ r
-    tz      <- liftIO . loadSystemTZ . tail <=< getTZFile . tshTZFile . trHeader $ r
+    tz      <- liftIO . loadSystemTZ . dropWhile (== ':') <=< getTZFile . tshTZFile . trHeader $ r
     units   <- getLevelUnits . trLevelUnits $ r
 
     let beginUTC = localTimeToUTCTZ' tz begin
         endUTC   = localTimeToUTCTZ' tz end
         nextUTC  = step `addUTCTime` beginUTC
-        years    = groupBy ((==) `on` yot) [beginUTC, nextUTC .. endUTC]
+        years    = NE.groupBy ((==) `on` yot) [beginUTC, nextUTC .. endUTC]
         yot      = yearOfTime :: UTCTime -> Int
 
     let tides' times = do
-            let startYear = yearOfTime $ head times
+            let startYear = yearOfTime $ NE.head times
                 yearNum = fromIntegral startYear - baseYear
 
             nodeFactors  <- mapM (`getNodeFactor`  yearNum) indices
@@ -62,19 +63,19 @@ tides station begin end step = do
                 tide    = evaluate series
                 tide'   = evaluate series'
 
-                heights = map (tide . toHours . timeOfTheYear) times
-                ztimes  = map (toZonedTime tz) times
+                heights = NE.map (tide . toHours . timeOfTheYear) times
+                ztimes  = NE.map (toZonedTime tz) times
 
-                beginHour = toHours . timeOfTheYear $ head times
-                endHour   = toHours . timeOfTheYear $ last times
+                beginHour = toHours . timeOfTheYear $ NE.head times
+                endHour   = toHours . timeOfTheYear $ NE.last times
                 hours = takeWhile (< endHour) [beginHour ..] ++ [endHour]
                 slots = zip hours (drop 1 hours)
                 reversals = filter (\(t0, t1) -> tide' t0 * tide' t1 <= 0) slots
                 events = concatMap findEvents reversals
                 findEvents = map toTideEvent . extrema series (1/240) -- 15s
                 toTideEvent = fmap . first $ toZonedTime tz . yhTimeToUtcTime . YHTime startYear
 
-            return (zip ztimes heights, events)
+            return (NE.zip ztimes heights, events)
 
           where
             d2r d = d * (pi / 180)
@@ -84,7 +85,7 @@ tides station begin end step = do
 
     predictions <- mapM tides' years
 
-    return (concatMap fst predictions, concatMap snd predictions, units, tz)
+    return (concatMap (NE.toList . fst) predictions, concatMap snd predictions, units, tz)
 
 -- Prefer the earlier time to the later time when LT is ambiguous
 -- This matches the behaviour of xtide

default.nix

@@ -1,7 +1,8 @@
 # vim: et:sw=2:sts=2
 
 { stdenv, lib, callPackage, mkDerivation, harmonicsType ? "free"
-, base, base-compat, containers, directory, filepath, hspec, hspec-golden, mtl, process, QuickCheck, random, time, time-locale-compat, tz
+, base, base-compat, containers, directory, filepath, hspec, hspec-golden
+, infinite-list, mtl, process, QuickCheck, random, time, time-locale-compat, tz
 , pkgs
 }:
 
@@ -19,8 +20,8 @@ in
     libraryHaskellDepends = [ base directory filepath ];
     librarySystemDepends = [ tcd ];
     executableHaskellDepends = [
-      base containers directory filepath mtl process QuickCheck random
-      time time-locale-compat tz ];
+      base containers directory filepath infinite-list mtl process QuickCheck
+      random time time-locale-compat tz ];
     executableSystemDepends = [ tcd ];
     testHaskellDepends = [
       base base-compat directory filepath hspec hspec-golden mtl process