-% -----------------------------------------------------------------------------
-% $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 #-}
-module GHC.Err
+{-# OPTIONS_GHC -fno-implicit-prelude #-}
+{-# OPTIONS_HADDOCK hide #-}
+-----------------------------------------------------------------------------
+-- |
+-- 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
, noMethodBindingError
, patError
, recSelError
, recConError
- , runtimeError -- :: Addr# -> a -- Addr# points to UTF8 encoded C string
+ , runtimeError -- :: Addr# -> a -- Addr# points to UTF8 encoded C string
+
+ , absentErr -- :: a
+ , divZeroError -- :: a
+ , overflowError -- :: a
- , absentErr, parError -- :: a
- , seqError -- :: a
+ , error -- :: String -> a
+ , assertError -- :: String -> Bool -> a -> a
- , error -- :: String -> a
- , assertError -- :: String -> Bool -> a -> a
-
- , undefined -- :: a
+ , undefined -- :: a
) where
+#ifndef __HADDOCK__
import GHC.Base
import GHC.List ( span )
import GHC.Exception
+#endif
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{Error-ish functions}
-%* *
+%* *
%*********************************************************
\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
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{Compiler generated errors + local utils}
-%* *
+%* *
%*********************************************************
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}
recSelError, recConError, irrefutPatError, runtimeError,
- nonExhaustiveGuardsError, patError, noMethodBindingError
- :: Addr# -> a -- All take a UTF8-encoded C string
+ nonExhaustiveGuardsError, patError, noMethodBindingError
+ :: Addr# -> a -- All take a UTF8-encoded C string
-recSelError s = throw (RecSelError (unpackCStringUtf8# s)) -- No location info unfortunately
-runtimeError s = error (unpackCStringUtf8# s) -- No location info unfortunately
+recSelError s = throw (RecSelError (unpackCStringUtf8# s)) -- No location info unfortunately
+runtimeError s = error (unpackCStringUtf8# s) -- No location info unfortunately
nonExhaustiveGuardsError s = throw (PatternMatchFail (untangle s "Non-exhaustive guards in"))
-irrefutPatError s = throw (PatternMatchFail (untangle s "Irrefutable pattern failed for pattern"))
-recConError s = throw (RecConError (untangle s "Missing field in record construction"))
+irrefutPatError s = throw (PatternMatchFail (untangle s "Irrefutable pattern failed for pattern"))
+recConError s = throw (RecConError (untangle s "Missing field in record construction"))
noMethodBindingError s = throw (NoMethodError (untangle s "No instance nor default method for class operation"))
-patError s = throw (PatternMatchFail (untangle s "Non-exhaustive patterns in"))
+patError s = throw (PatternMatchFail (untangle s "Non-exhaustive patterns in"))
assertError :: Addr# -> Bool -> a -> a
assertError str pred v
(untangle coded message) expects "coded" to be of the form
- "location|details"
+ "location|details"
It prints
- location message details
+ location message details
\begin{code}
untangle :: Addr# -> String -> String
(location, details)
= case (span not_bar coded_str) of { (loc, rest) ->
- case rest of
- ('|':det) -> (loc, ' ' : det)
- _ -> (loc, "")
- }
+ case rest of
+ ('|':det) -> (loc, ' ' : det)
+ _ -> (loc, "")
+ }
not_bar c = c /= '|'
\end{code}
+
+Divide by zero and arithmetic overflow.
+We put them here because they are needed relatively early
+in the libraries before the Exception type has been defined yet.
+
+\begin{code}
+{-# NOINLINE divZeroError #-}
+divZeroError :: a
+divZeroError = throw (ArithException DivideByZero)
+
+{-# NOINLINE overflowError #-}
+overflowError :: a
+overflowError = throw (ArithException Overflow)
+\end{code}
+
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