Add tool-requirements subcommand

app/ghcup-gen/GHCupInfo.hs

@@ -0,0 +1,11 @@
+module GHCupInfo where
+
+import           GHCupDownloads
+import           ToolRequirements
+import           GHCup.Types
+
+
+ghcupInfo :: GHCupInfo
+ghcupInfo = GHCupInfo { _toolRequirements = toolRequirements
+                      , _ghcupDownloads   = ghcupDownloads
+                      }

app/ghcup-gen/Main.hs

@@ -9,9 +9,10 @@
 
 module Main where
 
+import           GHCup.Types
 import           GHCup.Types.JSON               ( )
 import           GHCup.Utils.Logger
-import           GHCupDownloads
+import           GHCupInfo
 
 import           Data.Aeson                     ( eitherDecode )
 import           Data.Aeson.Encode.Pretty
@@ -135,7 +136,7 @@ main = do
           GenJSON gopts -> do
             let
               bs = encodePretty' (defConfig { confIndent = Spaces 2 })
-                                 ghcupDownloads
+                                 ghcupInfo
             case gopts of
               GenJSONOpts { output = Nothing }        -> L.hPutStr stdout bs
               GenJSONOpts { output = Just StdOutput } -> L.hPutStr stdout bs
@@ -159,7 +160,7 @@ main = do
 
  where
   valAndExit f contents = do
-    av <- case eitherDecode contents of
+    (GHCupInfo _ av) <- case eitherDecode contents of
       Right r -> pure r
       Left  e -> die (color Red $ show e)
     myLoggerT (LoggerConfig True (B.hPut stdout) (\_ -> pure ())) (f av)

app/ghcup-gen/ToolRequirements.hs

@@ -0,0 +1,94 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE QuasiQuotes       #-}
+
+module ToolRequirements where
+
+import           GHCup.Types
+import           GHCup.Utils.String.QQ
+
+import qualified Data.Map                      as M
+
+
+
+-- | Currently 'GHC' is used for both GHC and cabal to simplify
+-- this, until we need actual separation.
+toolRequirements :: ToolRequirements
+toolRequirements = M.fromList
+  [ ( GHC
+    , M.fromList
+      [ ( Nothing
+        , M.fromList
+          [ ( Linux UnknownLinux
+            , M.fromList
+              [ ( Nothing
+                , Requirements
+                  []
+                  [s|You need the following packages: curl g++ gcc gmp make ncurses realpath xz-utils. Consult your distro documentation on the exact names of those packages.|]
+                )
+              ]
+            )
+          , ( Linux Alpine
+            , M.fromList
+              [ ( Nothing
+                , Requirements
+                  [ "curl"
+                  , "gcc"
+                  , "g++"
+                  , "gmp-dev"
+                  , "ncurses-dev"
+                  , "libffi-dev"
+                  , "make"
+                  , "xz"
+                  , "tar"
+                  , "perl"
+                  ]
+                  ""
+                )
+              ]
+            )
+          , ( Linux Ubuntu
+            , M.fromList
+              [ ( Nothing
+                , Requirements
+                  [ "build-essential"
+                  , "curl"
+                  , "libgmp-dev"
+                  , "libffi-dev"
+                  , "libncurses-dev"
+                  , "libtinfo5"
+                  ]
+                  ""
+                )
+              ]
+            )
+          , ( Darwin
+            , M.fromList
+              [ ( Nothing
+                , Requirements
+                  []
+                  "On OS X, in the course of running ghcup you will be given a dialog box to install the command line tools. Accept and the requirements will be installed for you. You will then need to run the command again."
+                )
+              ]
+            )
+          , ( FreeBSD
+            , M.fromList
+              [ ( Nothing
+                , Requirements
+                  [ "curl"
+                  , "gcc"
+                  , "gmp"
+                  , "gmake"
+                  , "ncurses"
+                  , "perl5"
+                  , "libffi"
+                  , "libiconv"
+                  ]
+                  ""
+                )
+              ]
+            )
+          ]
+        )
+      ]
+    )
+  ]