diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # A Haskell library for the GitLab web API
 
-A library that interacts with a GitLab server's API. It supports
-queries about and updates to:
+This library interacts with a GitLab server's API. It supports queries
+about and updates to:
 
 * Branches
 * Commits
diff --git a/gitlab-haskell.cabal b/gitlab-haskell.cabal
--- a/gitlab-haskell.cabal
+++ b/gitlab-haskell.cabal
@@ -1,21 +1,11 @@
-cabal-version: 1.12
+cabal-version: 2.4
 name:           gitlab-haskell
 category:       Git
-version:        0.1.0.0
+version:        0.1.0.1
 synopsis:       A Haskell library for the GitLab web API
 description:
   This Haskell library queries and updates the database of a GitLab instance using the GitLab web API: <https://docs.gitlab.com/ee/api/>
   .
-  An example that returns projects for which issue creation is enabled is:
-  .
-  > projectsWithIssuesEnabled :: IO [Project]
-  > projectsWithIssuesEnabled = runGitLab myConfig $ filter (issueEnabled . issues_enabled) <$> allProjects
-  >   where myConfig = defaultGitLabServer
-  >             { url = "https://gitlab.example.com"
-  >             , token = "my_access_token" }
-  >         issueEnabled Nothing = False
-  >         issueEnabled (Just t) = t
-  .
   Unsurprisingly, GitLab hosts this Haskell library: <https://gitlab.com/robstewart57/gitlab-haskell>
  
                 
@@ -24,7 +14,7 @@
 author:         Rob Stewart
 maintainer:     robstewart57@gmail.com
 copyright:      2019 Rob Stewart, Heriot-Watt University
-license:        BSD3
+license:        BSD-3-Clause
 license-file:   LICENSE
 build-type:     Simple
 extra-source-files:
@@ -61,13 +51,9 @@
               , aeson
               , bytestring
               , text
-              , async
               , http-types
-              , containers
-              , random
-              , array
-              , time
               , transformers
               , unliftio
               , unliftio-core
   default-language: Haskell2010
+  ghc-options: -Wall
diff --git a/src/GitLab/API/Commits.hs b/src/GitLab/API/Commits.hs
--- a/src/GitLab/API/Commits.hs
+++ b/src/GitLab/API/Commits.hs
@@ -31,8 +31,8 @@
   gitlab (commitsAddr projectId)
   where
     commitsAddr :: Int -> Text
-    commitsAddr projectId =
-      "/projects/" <> T.pack (show projectId) <> "/repository" <> "/commits"
+    commitsAddr projId =
+      "/projects/" <> T.pack (show projId) <> "/repository" <> "/commits"
 
 -- | returns a commit for the given project and commit hash, if such
 -- a commit exists.
@@ -52,9 +52,9 @@
   gitlabOne (commitsAddr projectId)
   where
     commitsAddr :: Int -> Text
-    commitsAddr projectId =
+    commitsAddr projId =
       "/projects/"
-      <> T.pack (show projectId)
+      <> T.pack (show projId)
       <> "/repository"
       <> "/commits"
       <> "/" <> hash
diff --git a/src/GitLab/API/Groups.hs b/src/GitLab/API/Groups.hs
--- a/src/GitLab/API/Groups.hs
+++ b/src/GitLab/API/Groups.hs
@@ -11,20 +11,11 @@
 -}
 module GitLab.API.Groups where
 
-import Control.Concurrent.Async
-import Control.Monad
 import Control.Monad.IO.Class
-import Control.Monad.Trans.Reader
-import Data.Aeson
-import qualified Data.ByteString.Lazy as BSL
 import Data.Maybe
 import Data.Text (Text)
 import qualified Data.Text as T
-import qualified Data.Text.Encoding as T
-import GHC.Generics
-import Network.HTTP.Conduit
 import Network.HTTP.Types.Status
-import Network.HTTP.Types.URI
 
 import GitLab.API.Members
 import GitLab.API.Users
@@ -49,7 +40,8 @@
   -> AccessLevel -- ^ level of access granted
   -> User -- ^ the user
   -> GitLab m (Either Status Member)
-addUserToGroup groupName access user = addUserToGroup' groupName access (user_id user)
+addUserToGroup groupName access usr =
+  addUserToGroup' groupName access (user_id usr)
 
 -- | adds a list of users to a group.
 addUsersToGroup ::
diff --git a/src/GitLab/API/Issues.hs b/src/GitLab/API/Issues.hs
--- a/src/GitLab/API/Issues.hs
+++ b/src/GitLab/API/Issues.hs
@@ -11,34 +11,23 @@
 -}
 module GitLab.API.Issues where
 
-import Control.Concurrent.Async
-import Control.Monad
 import Control.Monad.IO.Class
 import Control.Monad.IO.Unlift
-import Control.Monad.Trans.Reader
-import Data.Array.IO
-import Data.List
-import Data.Text (Text)
 import qualified Data.Text as T
-import Data.Time.Calendar
-import Network.HTTP.Types.Status
-import System.IO
-import System.Random
-import UnliftIO.Async
 
 import GitLab.WebRequests.GitLabWebCalls
 import GitLab.Types
 
 -- | returns all issues against a project.
 projectOpenedIssues ::
-     (MonadIO m)
+     (MonadIO m, MonadUnliftIO m)
   => Project -- ^ the project
   -> GitLab m [Issue]
 projectOpenedIssues = projectOpenedIssues' . project_id
 
 -- | returns all issues against a project given its project ID.
 projectOpenedIssues' ::
-     (MonadIO m)
+     (MonadIO m, MonadUnliftIO m)
   => Int -- ^ the project ID
   -> GitLab m [Issue]
 projectOpenedIssues' projectId = do
@@ -51,11 +40,11 @@
      (MonadIO m)
   => User -- ^ the user
   -> GitLab m [Issue]
-userIssues user =
+userIssues usr =
   gitlabWithAttrs addr attrs
   where
     addr = "/issues"
     attrs = T.pack $
       "&author_id="
-      <> show (user_id user)
+      <> show (user_id usr)
       <> "&scope=all"
diff --git a/src/GitLab/API/Members.hs b/src/GitLab/API/Members.hs
--- a/src/GitLab/API/Members.hs
+++ b/src/GitLab/API/Members.hs
@@ -11,16 +11,10 @@
 -}
 module GitLab.API.Members where
 
-import Control.Concurrent.Async
-import Control.Monad
 import Control.Monad.IO.Class
-import Control.Monad.Trans.Reader
-import Data.List
 import Data.Text (Text)
 import qualified Data.Text as T
-import Data.Time.Calendar
 import Network.HTTP.Types.Status
-import System.IO
 
 import GitLab.Types
 import GitLab.WebRequests.GitLabWebCalls
@@ -61,8 +55,8 @@
      -> AccessLevel -- ^ level of access
      -> User -- ^ the user
      -> GitLab m (Either Status Member)
-addMemberToProject project access user =
-  addMemberToProject' (project_id project) access (user_id user)
+addMemberToProject project access usr =
+  addMemberToProject' (project_id project) access (user_id usr)
 
 -- | adds a user to a project with the given access level, given the
 -- project's ID and the user's ID. Returns @Right Member@ for each
diff --git a/src/GitLab/API/Projects.hs b/src/GitLab/API/Projects.hs
--- a/src/GitLab/API/Projects.hs
+++ b/src/GitLab/API/Projects.hs
@@ -11,25 +11,14 @@
 -}
 module GitLab.API.Projects where
 
-import Control.Monad
 import Control.Monad.IO.Class
 import Control.Monad.IO.Unlift
-import Control.Monad.Trans.Reader
-import Data.Aeson
-import qualified Data.ByteString.Lazy as BSL
 import Data.List
-import Data.Map (Map)
-import qualified Data.Map as Map
 import Data.Maybe
 import Data.Text (Text)
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as T
-import Data.Time.Clock
-import GHC.Generics
-import Network.HTTP.Conduit
-import Network.HTTP.Types.Status
 import Network.HTTP.Types.URI
-import System.IO
 import UnliftIO.Async
 
 import GitLab.API.Commits
@@ -52,11 +41,11 @@
   => Text -- ^ name or namespace of the project
   -> GitLab m [Project]
 projectForks projectName = do
-  let path =
+  let urlPath =
         "/projects/" <>
         T.decodeUtf8 (urlEncode False (T.encodeUtf8 projectName)) <>
         "/forks"
-  gitlab path
+  gitlab urlPath
 
 -- | searches for a 'Project' with the given project ID, returns
 -- 'Nothing' if a project with the given ID is not found.
@@ -64,8 +53,8 @@
   => Int -- ^ project ID
   -> GitLab m (Maybe Project)
 searchProjectId projectId = do
-  let path = T.pack ("/projects/" <> show projectId)
-  gitlabOne path
+  let urlPath = T.pack ("/projects/" <> show projectId)
+  gitlabOne urlPath
 
 -- | gets all projects with the given project name.
 --
@@ -119,9 +108,9 @@
   userMaybe <- searchUser username
   case userMaybe of
     Nothing -> return Nothing
-    Just user -> Just <$> gitlab (path (user_id user))
+    Just usr -> Just <$> gitlab (urlPath (user_id usr))
   where
-    path userId = "/users/" <> T.pack (show userId) <> "/projects"
+    urlPath userId = "/users/" <> T.pack (show userId) <> "/projects"
 
 -- | gets the 'GitLab.Types.Project' against which the given 'Issue'
 -- was created.
@@ -138,12 +127,12 @@
 -- user has created issues for.
 issuesCreatedByUser :: (MonadUnliftIO m, MonadIO m) => Text -> GitLab m (Maybe (User,[Project]))
 issuesCreatedByUser username = do
-  user <- searchUser username
-  case user of
+  user_maybe <- searchUser username
+  case user_maybe of
     Nothing -> return Nothing
     Just usr -> do
-      issues <- userIssues usr
-      projects <- mapConcurrently projectOfIssue issues
+      usersIssues <- userIssues usr
+      projects <- mapConcurrently projectOfIssue usersIssues
       return (Just (usr, projects))
 
 -- | searches for all projects with the given name, and returns a list
@@ -157,10 +146,14 @@
   projects <- projectsWithName projectName
   mapM processProject projects
   where
+    processProject ::
+         (MonadUnliftIO m, MonadIO m)
+      => Project
+      -> GitLab m (Project, [Issue], [User])
     processProject proj = do
-      issues <- projectOpenedIssues proj
-      let authors = map issue_author issues
-      return (proj, issues, authors)
+      (openIssues :: [Issue]) <- projectOpenedIssues proj
+      let authors = map issue_author openIssues
+      return (proj, openIssues, authors)
 
 -- | returns a (namespace,members) tuple for the given 'Project',
 -- where namespace is the namespace of the project
@@ -187,7 +180,7 @@
   pipes <- pipelines project
   case pipes of
     [] -> return False
-    (x:xs) -> return (pipeline_status x == "success")
+    (x:_) -> return (pipeline_status x == "success")
 
 -- | searches for a username, and returns a user ID for that user, or
 -- 'Nothing' if a user cannot be found. 
@@ -195,7 +188,7 @@
   => Text -- ^ name or namespace of project 
   -> GitLab m (Maybe Int)
 namespacePathToUserId namespacePath = do
-  user <- searchUser namespacePath
-  case user of
+  user_maybe <- searchUser namespacePath
+  case user_maybe of
     Nothing -> return Nothing
-    Just user -> return (Just (user_id user))
+    Just usr -> return (Just (user_id usr))
diff --git a/src/GitLab/API/RepositoryFiles.hs b/src/GitLab/API/RepositoryFiles.hs
--- a/src/GitLab/API/RepositoryFiles.hs
+++ b/src/GitLab/API/RepositoryFiles.hs
@@ -32,8 +32,8 @@
   -> Text -- ^ the file path
   -> Text -- ^ name of the branch, tag or commit
   -> GitLab m (Maybe RepositoryFile)
-repositoryFiles' projectId filePath ref =
-  gitlabWithAttrsOne addr ("&ref=" <> ref)
+repositoryFiles' projectId filePath reference =
+  gitlabWithAttrsOne addr ("&ref=" <> reference)
   where
     addr =
       "/projects/"
diff --git a/src/GitLab/API/Users.hs b/src/GitLab/API/Users.hs
--- a/src/GitLab/API/Users.hs
+++ b/src/GitLab/API/Users.hs
@@ -11,25 +11,10 @@
 -}
 module GitLab.API.Users where
 
-import Control.Concurrent.Async
-import Control.Monad
 import Control.Monad.IO.Class
-import Control.Monad.Trans.Reader
-import Data.Aeson
-import qualified Data.ByteString.Lazy as BSL
 import Data.List
-import Data.Map (Map)
-import qualified Data.Map as Map
 import Data.Maybe
 import Data.Text (Text)
-import qualified Data.Text as T
-import qualified Data.Text.Encoding as T
-import Data.Time.Clock
-import GHC.Generics
-import Network.HTTP.Conduit
-import Network.HTTP.Types.Status
-import Network.HTTP.Types.URI
-import System.IO
 
 import GitLab.Types
 import GitLab.WebRequests.GitLabWebCalls
diff --git a/src/GitLab/Types.hs b/src/GitLab/Types.hs
--- a/src/GitLab/Types.hs
+++ b/src/GitLab/Types.hs
@@ -36,16 +36,11 @@
   , MergeRequest(..)
   ) where
 
-import qualified Data.ByteString.Lazy as BSL
 import Data.Aeson
 import Data.Text (Text)
 import GHC.Generics
-import qualified Data.Text as T
-import qualified Data.Text.Encoding as T
 import Network.HTTP.Conduit
--- import APICalls
 import Control.Monad.Trans.Reader
-import Network.Connection (TLSSettings (..))
 
 -- | type synonym for all GitLab actions.
 type GitLab m a = ReaderT GitLabState m a
diff --git a/src/GitLab/WebRequests/GitLabWebCalls.hs b/src/GitLab/WebRequests/GitLabWebCalls.hs
--- a/src/GitLab/WebRequests/GitLabWebCalls.hs
+++ b/src/GitLab/WebRequests/GitLabWebCalls.hs
@@ -11,7 +11,6 @@
   , gitlabPost
   ) where
 
-import Network.Connection (TLSSettings (..))
 import Network.HTTP.Conduit
 import qualified Data.ByteString.Lazy as BSL
 import Data.Text (Text)
@@ -19,7 +18,6 @@
 import qualified Data.Text.Encoding as T
 import Data.Aeson
 import qualified Control.Exception as E
-import System.IO
 import Network.HTTP.Types.Status
 import GitLab.Types
 import Control.Monad.Trans.Reader
@@ -42,10 +40,12 @@
                 , requestBody = RequestBodyBS (T.encodeUtf8 dataBody) }
   res <- liftIO $ tryGitLab 0 request (retries cfg) manager Nothing
   case responseStatus res of
-    status@(Status 404 msg) -> return (Left status)
-    status@(Status 409 msg) -> return (Left status)
+    resp@(Status 404 _msg) -> return (Left resp)
+    resp@(Status 409 _msg) -> return (Left resp)
     _ -> return (case parseBSOne (responseBody res) of
-                   Just x -> Right x)
+                   Just x -> Right x
+                   Nothing -> Left $
+                     mkStatus 409 "unable to parse POST response")
 
 tryGitLab ::
      Int -- ^ the current retry count
@@ -54,12 +54,12 @@
   -> Manager -- ^ HTTP manager
   -> Maybe HttpException -- ^ the exception to report if maximum retries met
   -> IO (Response BSL.ByteString)
-tryGitLab i request retries manager ex
-  | i == retries = error (show ex)
+tryGitLab i request maxRetries manager lastException
+  | i == maxRetries = error (show lastException)
   | otherwise =
       httpLbs request manager
       `E.catch`
-        \ex -> tryGitLab (i+1) request retries manager (Just ex)
+        \ex -> tryGitLab (i+1) request maxRetries manager (Just ex)
 
 parseBSOne :: FromJSON a => BSL.ByteString -> Maybe a
 parseBSOne bs =
@@ -142,5 +142,5 @@
   in findPages hdrs
   where
     findPages [] = 1 -- error "cannot find X-Total-Pages in header"
-    findPages (("X-Total-Pages",bs):xs) = read (T.unpack (T.decodeUtf8 bs))
+    findPages (("X-Total-Pages",bs):_) = read (T.unpack (T.decodeUtf8 bs))
     findPages (_:xs) = findPages xs