BuckleScript looks very interesting. Semantic mapping and very small potential output are rare. GPLv2 would present some challenges using it commercially though.
Many compilers are released under the GPL license. Generally speaking[1], the output of the compiler is not subject to the license terms of the GPL, just as a document created by a GPL'ed word processor need not be licensed under the GPL.
[1]: There could conceivably be GPL code linked with your code in the final output, but I don't think people would release a compiler like that without big notices unless they're specifically trying to trick people into having to buy commercial licenses or something like that.
