id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
7593	Unable to print exceptions of unicode identifiers	dagit		"I suspect this is windows specific but I'm not certain (I couldn't reproduce it with an older ghc on osx).

Here is an example of the problem:
{{{
$ ghcii.sh
GHCi, version 7.6.1: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Prelude λ> ⇒

<interactive>:2:1: parse error on input `*** Exception: <stderr>: hPutChar: invalid argument (invalid character)
}}}

On other platforms the message looks more like: parse error on input `=>'

(not the automatic translation from ⇒ to =>, I think that's a separate bug related to the unicode symbols extension)

On windows my ghc is version 7.6.1. On OSX (where I could NOT reproduce the exception), my ghc is 7.4.1. I don't know if the GHC version matters. I strongly suspect this is a windows unicode issue.

GHC gives similar behavior to ghci, for example on this input:
{{{
⇒ = 1
}}}

ghc tries to give an error message but throws an exception printing ⇒."	bug	new	normal	7.8.1	Compiler	7.6.1				Windows	Unknown/Multiple	Incorrect warning at compile-time	Unknown