If a foreign pointer object corresponds to memory that was not allocated by the GC garbage collector, then a function to properly deallocate this memory when the Pointer object that stores this pointer is garbage collected should be called. The function should take a single argument, a foreign object, typically of type voidstar, which corresponds to the memory to deallocate.
i1 : malloc = foreignFunction("malloc", voidstar, ulong)
o1 = malloc
o1 : ForeignFunction
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i2 : free = foreignFunction("free", void, voidstar)
o2 = free
o2 : ForeignFunction
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i3 : finalizer = x -> (print("freeing memory at " | net x); free x)
o3 = finalizer
o3 : FunctionClosure
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i4 : for i to 9 do (x := malloc 8; registerFinalizer(x, finalizer))
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i5 : collectGarbage()
freeing memory at 0x7fa760066980
freeing memory at 0x7fa76006a0f0
freeing memory at 0x7fa7600573d0
freeing memory at 0x7fa760066280
freeing memory at 0x7fa760066260
freeing memory at 0x7fa760063eb0
freeing memory at 0x7fa760006fa0
freeing memory at 0x7fa760068720
freeing memory at 0x7fa760068740
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