Dear bug hunters,
ghci is unhappy with the attached module (stripped down version).
---
ralf/tmp> ghci -fglasgow-exts Arr.lhs
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 5.04, for Haskell 98.
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
\____/\/ /_/\____/|_| Type :? for help.
Loading package base ... linking ... done.
Loading package haskell98 ... linking ... done.
Compiling Arr ( Arr.lhs, interpreted )
ghc-5.04: panic! (the `impossible' happened, GHC version 5.04):
ByteCodeGen.schemeE P_
Please report it as a compiler bug to [EMAIL PROTECTED],
or http://sourceforge.net/projects/ghc/.
> Leaving GHCi.
ralf/tmp> ghc -O2 -c -Wall -fglasgow-exts Arr.lhs
Arr.lhs:22:
Warning: This binding for `s1#' shadows an existing binding
Arr.lhs:24:
Warning: This binding for `s2#' shadows an existing binding
Arr.lhs:27:
Warning: This binding for `s2#' shadows an existing binding
ralf/tmp> ghci -fglasgow-exts Arr.lhs
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 5.04, for Haskell 98.
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
\____/\/ /_/\____/|_| Type :? for help.
Loading package base ... linking ... done.
Loading package haskell98 ... linking ... done.
Skipping Arr ( Arr.lhs, ./Arr.o )
Ok, modules loaded: Arr.
Prelude Arr>
---
However, ghci loads precompiled code so it's not a show stopper.
Cheers, Ralf
% ghci -fglasgow-exts Arr.lhs
% ghc -O2 -c -Wall -fglasgow-exts Arr.lhs
Standard Int-indexed arrays.
> module Arr
> where
> import GHC.Exts
> import GHC.Base
> import GHC.ST
> data Arr x = Arr Int# (Array# x)
> update :: (x -> x) -> Int -> Arr x -> Arr x
> update f (I# i#) (Arr n# arr#)
> | 0# <=# i# && i# <# n# = runST (ST (upd f i# n# arr#))
> | otherwise = error "out of range"
> upd :: (x -> x) -> Int# -> Int# -> Array# x -> STRep s (Arr x)
> upd f i# n# arr# s1# = case newArray# n# undefined s1# of { (# s2#, marr# #) ->
> let fill j# s1#
> | j# >=# 0# = case indexArray# arr# j# of { (# x #) ->
> case writeArray# marr# j# x s1# of { s2# ->
> fill (j# -# 1#) s2# }}
> | otherwise = case indexArray# arr# i# of { (# x #) ->
> case writeArray# marr# i# (f x) s1# of { s2# ->
> case unsafeFreezeArray# marr# s2# of { (# s3#, arr2# #) ->
> (# s3#, Arr n# arr2# #) }}} in
> fill (n# -# 1#) s2# }
