Turkish “unless” is not biconditional unless the pragmatic context allows it.

Ebru Evcen, Umut Özge and Duygu Özge presented a poster on biconditionality of "unless" at the 8th Experimental Pragmatics Conference in Edinburgh on June 19-21, 2019.

http://www.xprag2019.ppls.ed.ac.uk/abstracts/evcen.pdf