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I think the hate for goto and the love of recursion have their origins with the ideas of the early 1970's when people like Dijkstra were obsessed with generatin

I think the hate for goto and the love of recursion have their origins with the ideas of the early 1970's when people like Dijkstra were obsessed with generating formal proofs from code. At the time they knew how to reason about recursion but not loops. And didn't know how to transform code with goto's. They thought that if you banned things like loops, gotos multiple returns, etc you could produce a language suitable for 'real mathematics'. Turns out this is mostly garbage. But 50 years later it gets taught and people still believe it. People think recursion is this super duper thing when it's not. And people think multiple returns, goto, and continue statements are bad when they are fine.

kbolino 3y ago
While such people may exist then and now, Dijkstra was not one of them. He was not complaining about the structured control flow of modern languages (yes, C is pretty modern relative to this concern) but unstructured jumps all over the place. The issue is not multiple return but multiple entry points and multiple exit destinations. Raw machine code and assembly had no notion of procedures or functions and so many early "high-level languages" didn't either. You could jump into the same chunk of code at different places and then jump back out of it to yet more random places. This was even seen as a feature by some because it enabled more aggressive code reuse. But the code quickly became unreadable and following the control flow through the code could become nigh-on impossible (the original "spaghetti code" which really could go from anywhere to anywhere at just about any time). This led to many subtle bugs which also in practice made the pieces of code less reusable since weaving through the code so much often picked up side-effects from its many different purposes. The use of structured procedures with a single entry point and well defined exit behavior (which we now call "return" because you exit back to the same place you came from every time) is what Dijkstra wanted, and he was right. It has become so well accepted that people don't even understand what he was complaining about because modern languages don't allow it.
bonki 3y ago
That makes a lot of sense, thanks for your reply!

kbolino 3y ago

While such people may exist then and now, Dijkstra was not one of them. He was not complaining about the structured control flow of modern languages (yes, C is pretty modern relative to this concern) but unstructured jumps all over the place. The issue is not multiple return but multiple entry points and multiple exit destinations. Raw machine code and assembly had no notion of procedures or functions and so many early "high-level languages" didn't either. You could jump into the same chunk of code at different places and then jump back out of it to yet more random places. This was even seen as a feature by some because it enabled more aggressive code reuse. But the code quickly became unreadable and following the control flow through the code could become nigh-on impossible (the original "spaghetti code" which really could go from anywhere to anywhere at just about any time). This led to many subtle bugs which also in practice made the pieces of code less reusable since weaving through the code so much often picked up side-effects from its many different purposes. The use of structured procedures with a single entry point and well defined exit behavior (which we now call "return" because you exit back to the same place you came from every time) is what Dijkstra wanted, and he was right. It has become so well accepted that people don't even understand what he was complaining about because modern languages don't allow it.

bonki 3y ago

That makes a lot of sense, thanks for your reply!