To reproduce,

• start a windows console
• Change the console's font to a ttf unicode font, like "Lucida Console".
• Type "chcp 65001" to set it to the UTF-8 code page.

test.hs

main = putStrLn "∷⇒∀→←⋯⊢"

Output to the console is garbled. runghc test.hs:

∷⇒∀→←⋯⊢
→←⋯⊢
⋯⊢
∷⇒∀→←⋯⊢→←⋯⊢←⋯⊢⋯⊢⊢⊢⊢<stdout>: hFlush: permission denied (Permission denied)

Piping works correctly. runghc test.hs > output && type output:

∷⇒∀→←⋯⊢

ghci fails. ghci test.hs

GHCi, version 6.12.3: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
[1 of 1] Compiling Main             ( test.hs, interpreted )
Ok, modules loaded: Main.
*Main> main
∷*** Exception: <stdout>: hPutChar: permission denied (Permission denied)
*Main>