Docs only

Summary: Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Test Plan: n/a

Reviewers: austin, Mikolaj

Reviewed By: austin, Mikolaj

Subscribers: thomie, carter

Differential Revision: https://phabricator.haskell.org/D446

5 files changed, 31 insertions, 12 deletions

diff --git a/compiler/deSugar/DsMonad.lhs b/compiler/deSugar/DsMonad.lhs
index c017a7cc01..1c707c4afc 100644
--- a/compiler/deSugar/DsMonad.lhs
+++ b/compiler/deSugar/DsMonad.lhs
@@ -221,7 +221,7 @@ initDs hsc_env mod rdr_env type_env fam_inst_env thing_inside
         }
   where
     -- Extend the global environment with a 'GlobalRdrEnv' containing the exported entities of
-    --   * 'Data.Array.Parallel'      iff '-XParallalArrays' specified (see also 'checkLoadDAP').
+    --   * 'Data.Array.Parallel'      iff '-XParallelArrays' specified (see also 'checkLoadDAP').
     --   * 'Data.Array.Parallel.Prim' iff '-fvectorise' specified.
     loadDAP thing_inside
       = do { dapEnv  <- loadOneModule dATA_ARRAY_PARALLEL_NAME      checkLoadDAP          paErr
diff --git a/compiler/iface/LoadIface.lhs b/compiler/iface/LoadIface.lhs
index faaea6c456..3b2f7f25c9 100644
--- a/compiler/iface/LoadIface.lhs
+++ b/compiler/iface/LoadIface.lhs
@@ -92,7 +92,7 @@ loadSrcInterface doc mod want_boot maybe_pkg
            Failed err      -> failWithTc err
            Succeeded iface -> return iface }
 
--- | Like loadSrcInterface, but returns a MaybeErr
+-- | Like 'loadSrcInterface', but returns a 'MaybeErr'.
 loadSrcInterface_maybe :: SDoc
                        -> ModuleName
                        -> IsBootInterface     -- {-# SOURCE #-} ?
@@ -111,7 +111,10 @@ loadSrcInterface_maybe doc mod want_boot maybe_pkg
            Found _ mod -> initIfaceTcRn $ loadInterface doc mod (ImportByUser want_boot)
            err         -> return (Failed (cannotFindInterface (hsc_dflags hsc_env) mod err)) }
 
--- | Load interface for a module.
+-- | Load interface directly for a fully qualified 'Module'.  (This is a fairly
+-- rare operation, but in particular it is used to load orphan modules
+-- in order to pull their instances into the global package table and to
+-- handle some operations in GHCi).
 loadModuleInterface :: SDoc -> Module -> TcM ModIface
 loadModuleInterface doc mod = initIfaceTcRn (loadSysInterface doc mod)
 
diff --git a/compiler/iface/TcIface.lhs b/compiler/iface/TcIface.lhs
index cabf311382..85ea0f94cc 100644
--- a/compiler/iface/TcIface.lhs
+++ b/compiler/iface/TcIface.lhs
@@ -184,9 +184,9 @@ We need to make sure that we have at least *read* the interface files
 for any module with an instance decl or RULE that we might want.
 
 * If the instance decl is an orphan, we have a whole separate mechanism
-  (loadOprhanModules)
+  (loadOrphanModules)
 
-* If the instance decl not an orphan, then the act of looking at the
+* If the instance decl is not an orphan, then the act of looking at the
   TyCon or Class will force in the defining module for the
   TyCon/Class, and hence the instance decl
 
diff --git a/compiler/typecheck/TcRnMonad.lhs b/compiler/typecheck/TcRnMonad.lhs
index cd414999af..1088c84d04 100644
--- a/compiler/typecheck/TcRnMonad.lhs
+++ b/compiler/typecheck/TcRnMonad.lhs
@@ -1250,6 +1250,9 @@ mkIfLclEnv mod loc = IfLclEnv { if_mod     = mod,
                                 if_tv_env  = emptyUFM,
                                 if_id_env  = emptyUFM }
 
+-- | Run an 'IfG' (top-level interface monad) computation inside an existing
+-- 'TcRn' (typecheck-renaming monad) computation by initializing an 'IfGblEnv'
+-- based on 'TcGblEnv'.
 initIfaceTcRn :: IfG a -> TcRn a
 initIfaceTcRn thing_inside
   = do  { tcg_env <- getGblEnv
diff --git a/compiler/typecheck/TcRnTypes.lhs b/compiler/typecheck/TcRnTypes.lhs
index e1762a8f73..2634aa852f 100644
--- a/compiler/typecheck/TcRnTypes.lhs
+++ b/compiler/typecheck/TcRnTypes.lhs
@@ -143,7 +143,11 @@ import qualified Language.Haskell.TH as TH
 The monad itself has to be defined here, because it is mentioned by ErrCtxt
 
 \begin{code}
+-- | Type alias for 'IORef'; the convention is we'll use this for mutable
+-- bits of data in 'TcGblEnv' which are updated during typechecking and
+-- returned at the end.
 type TcRef a     = IORef a
+-- ToDo: when should I refer to it as a 'TcId' instead of an 'Id'?
 type TcId        = Id
 type TcIdSet     = IdSet
 
@@ -153,9 +157,19 @@ type IfM lcl  = TcRnIf IfGblEnv lcl         -- Iface stuff
 
 type IfG  = IfM ()                          -- Top level
 type IfL  = IfM IfLclEnv                    -- Nested
+
+-- | Type-checking and renaming monad: the main monad that most type-checking
+-- takes place in.  The global environment is 'TcGblEnv', which tracks
+-- all of the top-level type-checking information we've accumulated while
+-- checking a module, while the local environment is 'TcLclEnv', which
+-- tracks local information as we move inside expressions.
 type TcRn = TcRnIf TcGblEnv TcLclEnv
-type RnM  = TcRn            -- Historical
-type TcM  = TcRn            -- Historical
+
+-- | Historical "renaming monad" (now it's just 'TcRn').
+type RnM  = TcRn
+
+-- | Historical "type-checking monad" (now it's just 'TcRn').
+type TcM  = TcRn
 \end{code}
 
 Representation of type bindings to uninstantiated meta variables used during
@@ -203,12 +217,11 @@ instance ContainsDynFlags (Env gbl lcl) where
 instance ContainsModule gbl => ContainsModule (Env gbl lcl) where
     extractModule env = extractModule (env_gbl env)
 
--- TcGblEnv describes the top-level of the module at the
+-- | 'TcGblEnv' describes the top-level of the module at the
 -- point at which the typechecker is finished work.
 -- It is this structure that is handed on to the desugarer
 -- For state that needs to be updated during the typechecking
--- phase and returned at end, use a TcRef (= IORef).
-
+-- phase and returned at end, use a 'TcRef' (= 'IORef').
 data TcGblEnv
   = TcGblEnv {
         tcg_mod     :: Module,         -- ^ Module being compiled
@@ -494,8 +507,8 @@ data IfLclEnv
 %*                                                                      *
 %************************************************************************
 
-The Global-Env/Local-Env story
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Note [The Global-Env/Local-Env story]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 During type checking, we keep in the tcg_type_env
         * All types and classes
         * All Ids derived from types and classes (constructors, selectors)