This seems to be related to

• https://ghc.haskell.org/trac/ghc/ticket/8425
• https://ghc.haskell.org/trac/ghc/ticket/7737
• https://ghc.haskell.org/trac/ghc/ticket/9128

but these are marked as closed for 7.8.3

Dominic Steinitz

dominic@steinitz.org

http://idontgetoutmuch.wordpress.com

On 27 Dec 2014, at 09:24, Dominic Steinitz <dominic@steinitz.org> wrote:

I am trying to resurrect the yarr package (https://hackage.haskell.org/package/yarr). Thanks to all the very helpful folk in the Haskell community it now compiles under 7.8.3 and the tests run apart from

~/Dropbox/Private/yarr/tests $ ./canny 1 50 100 tree.png
luminosity        8.41 ms,  5.33 tics per index
canny: Oops!  Entered absent arg $dVector1{v a6vi} [lid] Vector{tc rrL}
                         (VecList{tc rrR} (S{tc ruZ} Z{tc ruI}))
                         (VecList{tc rrR}
                            (S{tc ruZ}
                               (S{tc ruZ} (S{tc ruZ} (S{tc ruZ} (S{tc ruZ} Z{tc ruI})))))
                            (Word{(w) tc 32R}
                             -> Word{(w) tc 32R} -> IO{tc 32I} Word{(w) tc 32R}))
canny: thread blocked indefinitely in an MVar operation

Now according to the notes left by the original developer, this used to work under ghc 7.6.1.

What is this message telling me?

Let me know if I should provide more information.

Many thanks

Dominic Steinitz
dominic@steinitz.org
http://idontgetoutmuch.wordpress.com