Remove unnecessary ViewPatterns (#925)

lib/Echidna/Campaign.hs

@@ -1,6 +1,5 @@
 {-# LANGUAGE MultiWayIf #-}
 {-# LANGUAGE NoMonomorphismRestriction #-}
-{-# LANGUAGE ViewPatterns #-}
 {-# LANGUAGE GADTs #-}
 
 module Echidna.Campaign where
@@ -55,17 +54,20 @@ instance MonadCatch m => MonadCatch (RandT g m) where
 -- | Given a 'Campaign', checks if we can attempt any solves or shrinks without exceeding
 -- the limits defined in our 'CampaignConf'.
 isDone :: MonadReader EConfig m => Campaign -> m Bool
-isDone c | null (view tests c) = do
+isDone c | null c._tests = do
   conf <- asks (._cConf)
   pure $ c._ncallseqs * conf._seqLen >= conf._testLimit
-isDone (view tests -> ts) = do
+isDone c = do
   conf <- asks (._cConf)
   let res (Open  i)   = if i >= conf._testLimit then Just True else Nothing
       res Passed      = Just True
       res (Large i)   = if i >= conf._shrinkLimit then Just False else Nothing
       res Solved      = Just False
       res (Failed _)  = Just False
-  pure $ res . (.testState) <$> ts & if conf._stopOnFail then elem $ Just False else all isJust
+  let testResults = res . (.testState) <$> c._tests
+  let done = if conf._stopOnFail then Just False `elem` testResults
+                                 else all isJust testResults
+  pure done
 
 -- | Given a 'Campaign', check if the test results should be reported as a
 -- success or a failure.

lib/Echidna/Transaction.hs

@@ -1,6 +1,5 @@
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE GADTs #-}
-{-# LANGUAGE ViewPatterns #-}
 
 module Echidna.Transaction where
 
@@ -32,11 +31,11 @@ import Echidna.Types.Campaign (Campaign(..))
 hasSelfdestructed :: VM -> Addr -> Bool
 hasSelfdestructed vm addr = addr `elem` vm._tx._substate._selfdestructs
 
--- | If half a tuple is zero, make both halves zero. Useful for generating delays, since block number
--- only goes up with timestamp
+-- | If half a tuple is zero, make both halves zero. Useful for generating
+-- delays, since block number only goes up with timestamp
 level :: (Num a, Eq a) => (a, a) -> (a, a)
-level (elemOf each 0 -> True) = (0,0)
-level x                       = x
+level (x, y) | x == 0 || y == 0 = (0, 0)
+level x = x
 
 getSignatures :: MonadRandom m => SignatureMap -> Maybe SignatureMap -> m SignatureMap
 getSignatures hmm Nothing = return hmm