Refactor configureCompiler path addition for cleaner variable names

Author: yutotakano

cabal-install/src/Distribution/Client/ProjectPlanning.hs

@@ -500,27 +500,28 @@ configureCompiler
       )
       $ do
         liftIO $ info verbosity "Compiler settings changed, reconfiguring..."
-        let extraPath = fromNubList packageConfigProgramPathExtra
-        -- Add paths in the local config
-        progdb <- liftIO $ prependProgramSearchPath verbosity extraPath [] defaultProgramDb
-        -- Add paths in the global config
-        progdb' <- liftIO $ prependProgramSearchPath verbosity (fromNubList projectConfigProgPathExtra) [] progdb
-        let progdb'' = userSpecifyPaths (Map.toList (getMapLast packageConfigProgramPaths)) progdb'
-        result@(_, _, progdb''') <-
+        progdb <-
+          liftIO $
+            -- Add paths in the global config
+            prependProgramSearchPath verbosity (fromNubList projectConfigProgPathExtra) [] defaultProgramDb
+              -- Add paths in the local config
+              >>= prependProgramSearchPath verbosity (fromNubList packageConfigProgramPathExtra) []
+              >>= pure . userSpecifyPaths (Map.toList (getMapLast packageConfigProgramPaths))
+        result@(_, _, progdb') <-
           liftIO $
             Cabal.configCompilerEx
               hcFlavor
               hcPath
               hcPkg
-              progdb''
+              progdb
               verbosity
         -- Note that we added the user-supplied program locations and args
         -- for /all/ programs, not just those for the compiler prog and
         -- compiler-related utils. In principle we don't know which programs
         -- the compiler will configure (and it does vary between compilers).
         -- We do know however that the compiler will only configure the
         -- programs it cares about, and those are the ones we monitor here.
-        monitorFiles (programsMonitorFiles progdb''')
+        monitorFiles (programsMonitorFiles progdb')
 
         -- Note: There is currently a bug here: we are dropping unconfigured
         -- programs from the 'ProgramDb' when we re-use the cache created by