short description

Miranda is a modern functional programming language designed by David Turner of the University of Kent, with lazy evaluation, polymorphic strong typing, and a powerful module system. A program written in Miranda is typically 5 to 15 times shorter than the corresponding program in C or Java. The main features of Miranda are:

purely functional - no side effects
higher order - supports functional data
lazy - supports non strict functions and infinite data objects
list comprehensions
polymorphic strong typing
abstract data types and modules

The built in types of the language are numbers (unbounded size integers and double precision floating point), characters, lists, tuples, and functions. User defined types with arbitrary substructure can be introduced by writing type equations (so called `algebraic data types'). The language also has abstract data types and a simple but powerful module system with type security across module boundaries.

By way of a very brief example of Miranda style, here is a definition of the list of all prime numbers (an infinite data structure) using the sieve of Eratosthenes

        primes = sieve [2..]
                 where
                 sieve (p:x) = p : sieve [n | n<-x ; n mod p > 0]

The expression in square brackets is a `list comprehension' - it means list of n such that n drawn from x and n not divisible by p. The test for divisibility uses mod, the remainder operator. For comparison here is the solution in Java.

The Miranda system provides a self-contained interactive programming environment. The Miranda compiler works in conjunction with a screen editor (which can be vi or another editor of the user's choice). The type system enables a high proportion of semantic errors to be detected at compile time.

There is an online reference manual and a built in `make' feature which automatically keeps object code files up-to-date with their sources. The compiler generates an intermediate code based on combinatory logic, which is executed by a fast interpreter.

Research Software Limited was awarded a British Computer Society medal for the design of the Miranda system (BCS Awards, 1990).

Release Information

The Miranda system has been developed by Research Software Ltd, of Canterbury, England, a company formed to develop advanced functional programming systems. The Miranda system has been extensively tested and is running at 600 sites including 250 universities.