MLtonWorld.load works by attempting to invoke the same binary using CommandLine.name(). For a binary on PATH on most unix systems this yields just the binary name. But Posix.Process.exec requires the path to the binary. On Linux systems there's a fast workaround which is to use /proc/self/exe, but this isn't portable. A quick Google suggests this wants some kind of portable "Get path to current binary" functionality.

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