Languages usually have a foreign function interface (FFI for short) to interface with external libraries. That's not as easy as one could expect, even for langu

Languages usually have a foreign function interface (FFI for short) to interface with external libraries. That's not as easy as one could expect, even for languages that are "closer to the metal": I remember Pascal and C different parameters passing conventions, left to right vs right to left and the cleaning of stack... you need to use compiler directives and careful thinking. Also which memory manager you use and the fact that DLLs might not "see" the same address space. You mention Python that they say has an easy FFI with C. That's nice but it's usually used for the performance more than for reusing code.