Thanks Sterl, you're right, this was because I have don´t compiled with the -threaded flag, this works fine now.

This answer may be way off base, but if differences appear between ghci and compiled versions, I've often found its as simple as remembering to compile with the -threaded flag. The ghci runtime is threaded by default, as I understand it, while compiled binaries are not, and IO operations will block in very different fashions (i.e. in their own thread, or stalling the entire app) depending on the runtime.

Regards, sterl. Alvaro

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