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by kortex
1543 days ago
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Nope, unless you do some serious contortions and basically say that the universe is a lambda calculus that operates on each moment in time to produce a new view of reality. Computers that do anything useful have all manner of I/O. Highly oversimplified in modern architecture, but you can think of I/O as a bunch of memory cells that are DMA'd by external forces. Literally the exact opposite of functional, IO registers are the epitome of global mutable state. Then you have interrupts and the CPU operates in response to these events. The viewpoint of "computers are mutable state" is inherently better because of parsimony - it requires less degrees of indirection to explain what is happening. Just because you could shoehorn reality into a physical model, does not make it equally valid. You basically need to break it down to the Schrodinger equation level to have a purely functional model when even idealized gates are involved because propagation delay impacts things like how fast you can DMA. |
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Hey, physicists do it all the time. Having mathematical representations of how things work in the real world often turn out to give you complex devices that you wouldn't get by intuition alone. Thanks to doing it, we have Special Relativity and Schrodinger equations, that bring you advantages as GPS and insanely-high-speed networks.
There's nothing wrong with modelling interrupts and mutable state as static mathematical entities a.k.a. functions; and if you think it is, you don't know enough about functional programming - in fact, doing it allows for advanced tactics like automatic verification and very high scale generation of electronic devices.
Those less degrees of indirection may make it simple to build some kinds of programs; but they also introduce complexity in modelling the possible states of the system when you allow for arbitrary, unchecked side effects. So no, that representation is not inherently better - only most suited for some tasks than others; but the converse is also true for functional models of computation. If you think it is always better, it's because you're not taking all possible scenarios and utilities into account.
(Besides, as I already said elsewhere, "computers are mutable state" is not incompatible with functional representation; as mutable state can be represented with it). It seems that you're confusing mutable, wich is a property of computational devices, with 'imperative' which is a style of writing source code and defining relations between statements in your written program.
> Literally the exact opposite of functional, IO registers are the epitome of global mutable state.
Yup, you definitively don't know what functional programming is if you think you can't have global mutable state in it. In fact, every top-level Haskell program is defined as a global mutable IO monad...