Hello everybody, A short note about my progress on Psyco, the kind of compiler for Python. In its latest form it is a kind of just-in-time compiler, working at run-time. It consists of two parts: a language-independent "glue" part (which I more or less finished), and the inner loop of the Python interpreter rewritten in a special, resticted language. The "glue" part executes Python programs by running the interpreter, but not in the common way. The run-time data are split into what must be known to produce good processor code, and what need not be. Typically, we need to know at least which Python code to interpret before we can make good processor code that performs similarily; in the case of Python we will probably also need to know the type fields of the actual Python objects fed to the Python code; the processor code can be very efficiently optimized depending on the type. On the other hand, if the Python objects are, say, integers, then the same processor code can easily manipulate all possible integer values. The "glue" code is responsible for choosing which data goes into which category, and managing caches of the produced code. The Python-dependent part of the code either makes computations at compile-time (for compile-time-known values) or emits code to do it at run-time (for the rest). The choice between the two categories of data is not done statically; I mean, I didn't say "Python code and type fields are in category 1, the rest in category 2", which would amount to writing a JIT compiler with type-analysis. No; I let this separation be done based on the uses of the data. In two words, if I have a "switch" on data, or a call to function pointer, then knowing the data at compile time enables significant improvements, so I mark that data as "category 1"; as long as this does not occur data is in "category 2". This makes the approach quite general, I think. Experiment will be needed to know whether it performs reasonably well. Another interesting point to note is that this idea applies to any other interpreted language; all you need to do is rewrite the inner loop of the interpreter for the other language in a special way. Orthogonally, you can change the target processor by adapting parts of the "glue" code. More about it later, Armin.