ARM has introduced a set of extensions to the ARM architecture that will allow an ARM processor to directly execute Java bytecode: Jazelle (ARM Architecture Extensions for Java Applications). What do you think of a processor to facilitate code execution for functional languages (such as Erlang)?
You may want to look at Reduceron CPU: http://www.cs.york.ac.uk/fp/reduceron/
I think it might be useful as a co-processor for certain type of systems. I don't know if it has a wide applicability though.
I have seen a couple of projects that try to tackle this type of thinking such as Dalvik accelerators. Nothing specific in Erlang though.
Sure, it is technically possible. For instance, you might remember the Lisp processor from Symbolics at the beginning of the 80'ies. The problem is the commercial viability of such processors. The most used functional programming language (according to TIOBE) is JavaScript with 2% of the code market (and JavaScript is only partly a functional language). Such companies have gone bankrupt because mainstream processors could be updated often to benefit from the latest technology, while the size of their market only allowed to redesign the processor every few years. As a consequence, their processors, even with the advantage of running native functional code, were often slower than mainstream processors running a virtual machine.
I think the problem might be even worse than described by Pierre. Performance of current microprocessor architectures are heavily dependent on data and code caching, prefetching and pipelining of computations. Direct implementation of functional computations breaks all these optimizations. So the tight loop computations should be eager imperative register-machine code to be efficient. On the coarse grain level functional computations just don't need hardware support as JIT and even good static compiler can compile them to efficient register-machine code.
Java is not exactly functional but it's stack-machine Java Byte Code was initially planned as microprocessor instruction. This idea has proved to be infeasible due to incompatibility with pipelined code execution crippling the potential efficiency of the hardware Java processor. Java Byte Code only works out with a good complex JIT. For example Android Dalvik VM forgo JBC for register machine code to avoid JIT complexity problem.
Moreover, hardware/software trade-of is a very subtle matter as hardware always has limited flexibility and capacity. So it is usually more efficient to move all complex code analysis tasks to software (compiler/JIT). One example is the removal of hardware x86 emulation from Intel Itanium and replacing it by software binary translation from x86 to IA64.
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