GHCi crashes if a :def command gets a pattern-match error

Peter Hercek reports

% ghci
GHCi, version 6.10.1: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
Prelude> :def err (\_->return $ concat $ replicate (read "\"1\"") "a")
Prelude> :err
ghc: panic! (the 'impossible' happened)
   (GHC version 6.10.1 for i386-unknown-linux):
        Prelude.read: no parse

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

The "no parse" is quite correct: (read "\"1\"") :: Int should fail to parse. But it's wrong that a crashing :def should crash out of GHCi. Rather it should just return to the prompt, preferably with a failure message saying that running a :def failed.

Simon

Trac metadata

Trac field	Value
Version	6.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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