[project @ 2005-02-03 10:32:11 by ross]

[ghc-base.git] / GHC / Err.lhs

diff --git a/GHC/Err.lhs b/GHC/Err.lhs
index fb34ab5..85453aa 100644 (file)
--- a/GHC/Err.lhs
+++ b/GHC/Err.lhs
@@ -1,20 +1,25 @@
-% -----------------------------------------------------------------------------
-% $Id: Err.lhs,v 1.4 2002/04/11 12:03:43 simonpj Exp $
-%
-% (c) The University of Glasgow, 1994-2000
-%
-
-\section[GHC.Err]{Module @GHC.Err@}
-
-The GHC.Err module defines the code for the wired-in error functions,
-which have a special type in the compiler (with "open tyvars").
-
-We cannot define these functions in a module where they might be used
-(e.g., GHC.Base), because the magical wired-in type will get confused
-with what the typechecker figures out.
-
 \begin{code}
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -fno-implicit-prelude #-}
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  GHC.Err
+-- Copyright   :  (c) The University of Glasgow, 1994-2002
+-- License     :  see libraries/base/LICENSE
+-- 
+-- Maintainer  :  cvs-ghc@haskell.org
+-- Stability   :  internal
+-- Portability :  non-portable (GHC extensions)
+--
+-- The "GHC.Err" module defines the code for the wired-in error functions,
+-- which have a special type in the compiler (with \"open tyvars\").
+-- 
+-- We cannot define these functions in a module where they might be used
+-- (e.g., "GHC.Base"), because the magical wired-in type will get confused
+-- with what the typechecker figures out.
+-- 
+-----------------------------------------------------------------------------
+
+-- #hide
 module GHC.Err 
        (
          irrefutPatError
@@ -25,8 +30,8 @@ module GHC.Err
        , recConError
        , runtimeError              -- :: Addr#  -> a   -- Addr# points to UTF8 encoded C string
 
-       , absentErr, parError       -- :: a
-       , seqError                  -- :: a
+       , absentErr                -- :: a
+       , divZeroError             -- :: a
 
        , error                    -- :: String -> a
        , assertError              -- :: String -> Bool -> a -> a
@@ -34,9 +39,11 @@ module GHC.Err
        , undefined                -- :: a
        ) where
 
+#ifndef __HADDOCK__
 import GHC.Base
 import GHC.List     ( span )
 import GHC.Exception
+#endif
 \end{code}
 
 %*********************************************************
@@ -46,12 +53,13 @@ import GHC.Exception
 %*********************************************************
 
 \begin{code}
--- error stops execution and displays an error message
+-- | 'error' stops execution and displays an error message.
 error :: String -> a
 error s = throw (ErrorCall s)
 
+-- | A special case of 'error'.
 -- It is expected that compilers will recognize this and insert error
--- messages which are more appropriate to the context in which undefined 
+-- messages which are more appropriate to the context in which 'undefined'
 -- appears. 
 
 undefined :: a
@@ -68,11 +76,9 @@ Used for compiler-generated error message;
 encoding saves bytes of string junk.
 
 \begin{code}
-absentErr, parError, seqError :: a
+absentErr :: a
 
 absentErr = error "Oops! The program has entered an `absent' argument!\n"
-parError  = error "Oops! Entered GHCerr.parError (a GHC bug -- please report it!)\n"
-seqError  = error "Oops! Entered seqError (a GHC bug -- please report it!)\n"
 \end{code}
 
 \begin{code}
@@ -123,3 +129,13 @@ untangle coded message
        }
     not_bar c = c /= '|'
 \end{code}
+
+Divide by zero.  We put it here because it is needed relatively early
+in the libraries before the Exception type has been defined yet.
+
+\begin{code}
+{-# NOINLINE divZeroError #-}
+divZeroError :: a
+divZeroError = throw (ArithException DivideByZero)
+\end{code}
+