DescribeUnitId.hs

{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE Rank2Types #-}

module Distribution.Backpack.DescribeUnitId where

import Distribution.Compat.Prelude
import Prelude ()

import Distribution.Compat.Stack
import Distribution.ModuleName
import Distribution.Pretty
import Distribution.Simple.Utils
import Distribution.Types.ComponentName
import Distribution.Types.PackageId
import Distribution.Verbosity

import Text.PrettyPrint

-- Unit identifiers have a well defined, machine-readable format,
-- but this format isn't very user-friendly for users.  This
-- module defines some functions for solving common rendering
-- problems one has for displaying these.
--
-- There are three basic problems we tackle:
--
--  - Users don't want to see pkg-0.5-inplace-libname,
--    they want to see "library 'libname' from 'pkg-0.5'"
--
--  - Users don't want to see the raw component identifier, which
--    usually contains a wordy hash that doesn't matter.
--
--  - Users don't want to see a hash of the instantiation: they
--    want to see the actual instantiation, and they want it in
--    interpretable form.
--

-- | Print a Setup message stating (1) what operation we are doing,
-- for (2) which component (with enough details to uniquely identify
-- the build in question.)
setupMessage'
  :: Pretty a
  => Verbosity
  -> String
  -- ^ Operation being done (capitalized), on:
  -> PackageIdentifier
  -- ^ Package
  -> ComponentName
  -- ^ Component name
  -> Maybe [(ModuleName, a)]
  -- ^ Instantiation, if available.
  -- Polymorphic to take
  -- 'OpenModule' or 'Module'
  -> IO ()
setupMessage' verbosity msg pkgid cname mb_insts = withFrozenCallStack $ do
  noticeDoc verbosity $
    case mb_insts of
      Just insts
        | not (null insts) ->
            hang
              (msg_doc <+> text "instantiated with")
              2
              ( vcat
                  [ pretty k <+> text "=" <+> pretty v
                  | (k, v) <- insts
                  ]
              )
              $$ for_doc
      _ ->
        msg_doc <+> for_doc
  where
    msg_doc = text msg <+> text (showComponentName cname)
    for_doc = text "for" <+> pretty pkgid <<>> text "..."