Alice (programming language)
From Wikipedia, the free encyclopedia
Alice is a functional programming language designed by the Programming Systems Lab at Saarland University. It is a dialect of Standard ML, augmented with support for lazy evaluation, concurrency (multithreading and distributed computing via remote procedure calls) and constraint programming.
The Alice implementation from Saarland University uses the SEAM (Simple Extensible Abstract Machine) virtual machine. It is free software, and features just-in-time compilation to bytecode as well as native code for the x86 architecture.
Early versions of Alice ran on the Mozart/Oz VM, allowing interfacing between Alice and Oz code.
Alice's remote procedure calling depends on the virtual machine, because it may actually send code to be computed from one computer to another.
[edit] Example
Alice extends Standard ML with several primitives for lazy evaluation and concurrency. For example, threads may be created using the spawn keyword. Consider the naive algorithm for computing the Fibonacci numbers:
fun fib 0 = 0 | fib 1 = 1 | fib n = fib(n-1) + fib(n-2);
For large values of n, fib n will take a long time to compute. This computation can be performed in a separate thread by
val x = spawn fib n;
The variable x is now bound to a so-called "future". When an operation requires the actual value of x, it blocks until the thread is done with the computation. To exploit parallelism one could even define fib as follows:
fun fib 0 = 0 | fib 1 = 1 | fib n = spawn fib(n-1) + fib(n-2);
