playbooks/roles/fedora_packages/tasks/haskell.yml

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+---
+- name: Install ghc and hlint
+  dnf:
+    name:
+      - "@ghc:8.10"
+      - hlint
+    state: present

playbooks/roles/haskell/tasks/main.yml

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+---
+- name: Create directories for configuration
+  shell: mkdir ~/.ghc
+
+- name: Install ghci.conf
+  template:
+    src: templates/ghci.conf.j2
+    dest: ~/.ghc/ghci.conf
+
+- name: Install HLint.hs
+  template:
+    src: templates/HLint.hs.j2
+    dest: ~/.ghc/HLint.hs

playbooks/roles/haskell/templates/HLint.hs.j2

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+import "hint" HLint.Builtin.All
+import "hint" HLint.Default
+import "hint" HLint.Dollar
+
+import Data.Map
+import Control.Arrow
+import Control.Monad
+import Control.Monad.State
+
+warn = (\ x -> f $ g x) ==> f . g
+
+-- List
+warn = cycle [c] ==> repeat c
+
+warn = x == [] ==> null x where note = "generalize"
+warn = [] == x ==> null x where note = "generalize"
+
+warn = x /= [] ==> not (null x) where note = "generalize"
+warn = [] /= x ==> not (null x) where note = "generalize"
+
+warn = fst (unzip x) ==> map fst x
+warn = snd (unzip x) ==> map snd x
+
+warn "Use not . null" = length x > 0 ==> not (null x) where note = "increases laziness"
+warn "Use not . null" = length x >= 1 ==> not (null x) where note = "increases laziness"
+
+-- Map
+warn = map fst (Data.Map.toList x) ==> Data.Map.keys x
+warn = map snd (Data.Map.toList x) ==> Data.Map.elems x
+
+warn = foldr f v (Data.Map.elems x) ==> Data.Map.foldr f v x
+warn = Data.Maybe.fromMaybe d (Data.Map.lookup k m) ==> Data.Map.findWithDefault d k m
+
+-- Arrows
+
+warn = id *** id ==> id
+warn = Control.Arrow.first id ==> id
+warn = Control.Arrow.second id ==> id
+
+warn = Control.Arrow.first f (Control.Arrow.second g x) ==> (f Control.Arrow.*** g) x
+warn = Control.Arrow.second f (Control.Arrow.first g x) ==> (g Control.Arrow.*** f) x
+
+warn = Control.Arrow.first f (Control.Arrow.first g x) ==> Control.Arrow.first (f . g) x
+warn = Control.Arrow.second f (Control.Arrow.second g x) ==> Control.Arrow.second (f . g) x
+
+warn = (a *** b) ((c &&& d) x) ==> ((a . c) Control.Arrow.&&& (b . d)) x
+warn = (a *** b) ((c *** d) x) ==> ((a . c) Control.Arrow.*** (b . d)) x
+
+warn = Control.Arrow.first f ((a *** b) x) ==> ((f . a) Control.Arrow.*** b) x
+warn = Control.Arrow.second f ((a *** b) x) ==> (a Control.Arrow.*** (f . b)) x
+warn = (a *** b) (Control.Arrow.first f x) ==> ((a . f) Control.Arrow.*** b) x
+warn = (a *** b) (Control.Arrow.second f x) ==> (a Control.Arrow.*** (b . f)) x
+
+warn = Control.Arrow.first f ((a &&& b) x) ==> ((f . a) Control.Arrow.&&& b) x
+warn = Control.Arrow.second f ((a &&& b) x) ==> (a Control.Arrow.&&& (f . b)) x
+
+-- State
+
+warn = fmap f Control.Monad.State.get ==> Control.Monad.State.gets f
+warn = Control.Monad.liftM f Control.Monad.State.get ==> Control.Monad.State.gets f

playbooks/roles/haskell/templates/ghci.conf.j2

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+-- GHCi customization file
+
+-- vim: syntax=haskell expandtab
+
+-- some sections are comented out with comments starting with -- &,
+-- so you can uncomment them by removing this prefix to enamble them
+-- note: block comments do not work here, the same holds for layout rule
+
+
+-- Save to ~/.ghc/ghci.conf
+-- Most of the code was taken from the official Haskell wiki.
+-- https://wiki.haskell.org/GHC/GHCi
+
+-- set coloured prompt with loaded modules on separate line
+-- <https://coderwall.com/p/13h9bw/colored-ghci-prompt-with-and-modules-on-separate-lines>
+-- :set prompt "\ESC[1;34m%s\n\ESC[0;34m\x03BB> \ESC[m"
+--             -bold-blue-    -blue---- -lambda -black-
+
+-- Set all warning on by default
+-- but disable type defaults warning
+:set -Wall
+:set -Wno-type-defaults
+
+-- The following definitions were taken from "getting more out of ghci", the mini-tutorial
+-- <https://mail.haskell.org/pipermail/haskell-cafe/2007-September/032260.html>
+
+-- make commands helpful
+:{
+let { cmdHelp _   msg "--help" = return $ "putStrLn " ++ show msg
+    ; cmdHelp cmd _   other    = cmd other }
+:}
+
+-- :pwd, :ls
+let pwd _ = return "System.Directory.getCurrentDirectory >>= putStrLn"
+:def pwd cmdHelp pwd ":pwd\t\t\t-- print working directory"
+:{
+let ls p  = return $ "mapM_ putStrLn =<< System.Directory.getDirectoryContents "++show path
+            where {path = if (null p) then "." else p}
+:}
+:def ls cmdHelp ls ":ls [<path>]\t\t-- list directory (\".\" by default)"
+
+-- :redir
+:{
+let redir varcmd =
+     case break Data.Char.isSpace varcmd of
+     { (var,_:cmd) -> return $ unlines
+        [":set -fno-print-bind-result"
+        ,"tmp <- System.Directory.getTemporaryDirectory"
+        ,"(f,h) <- System.IO.openTempFile tmp \"ghci\""
+        ,"sto <- GHC.IO.Handle.hDuplicate System.IO.stdout"
+        ,"GHC.IO.Handle.hDuplicateTo h System.IO.stdout"
+        ,"System.IO.hClose h"
+        ,cmd
+        ,"GHC.IO.Handle.hDuplicateTo sto System.IO.stdout"
+        ,"let readFileNow f = readFile f >>= \\t->length t `seq` return t"
+        ,var++" <- readFileNow f"
+        ,"System.Directory.removeFile f"]
+      ; _ -> return "putStrLn \"usage: :redir <var> <cmd>\"" }
+:}
+:def redir cmdHelp redir ":redir <var> <cmd>\t-- execute <cmd>, redirecting stdout to <var>"
+
+-- :hlint
+-- requires hlint executable in PATH
+-- tries to load ~/.ghc/HLint.hs with additional hints
+:{
+:def hlint \extra -> return $ unlines
+        [":unset +t +s"
+        ,":set -w"
+        ,":redir hlintvar1 :show modules"
+        ,":cmd return $ \":! hlint --color --hint ~/.ghc/HLint.hs \" ++ unwords (map (takeWhile (/=',') . drop 2 . dropWhile (/= '(')) $ lines hlintvar1) ++ \" \" ++ " ++ show extra
+        ]
+:}