KRC is a lazy

Lazy evaluation

In programming language theory, lazy evaluation or call-by-need is an evaluation strategy which delays the evaluation of an expression until the value of this is actually required and which also avoids repeated evaluations...

 functional language developed by David Turner

David Turner (computer scientist)

Professor David Turner is a British computer scientist.He has a D.Phil. from the University of Oxford. He has held professorships at Queen Mary College, London, University of Texas at Austin and the University of Kent at Canterbury, where he now retains the post of Emeritus Professor.He is...

 in (or before?) 1981 based on SASL

SASL programming language

SASL is a purely functional programming language developed by David Turner at the University of St Andrews in 1972, based on the applicative subset of ISWIM. In 1976 Turner redesigned and reimplemented it as a non-strict language...

, with pattern matching

Pattern matching

In computer science, pattern matching is the act of checking some sequence of tokens for the presence of the constituents of some pattern. In contrast to pattern recognition, the match usually has to be exact. The patterns generally have the form of either sequences or tree structures...

, guard

Guard (computing)

In computer programming, a guard is a boolean expression that must evaluate to true if the program execution is to continue in the branch in question. The term is used at least in Haskell, Clean, Erlang, occam, Promela, OCaml and Scala programming languages. In Mathematica, guards are called...

s and ZF expressions (now more usually called list comprehensions).
Two implementations of KRC were written: David Turner's original one in BCPL

BCPL

BCPL is a procedural, imperative, and structured computer programming language designed by Martin Richards of the University of Cambridge in 1966.- Design :...

 running on EMAS

Edinburgh Multiple Access System

The Edinburgh Multi-Access System was a mainframe computer operating system developed at the University of Edinburgh, Scotland, during the 1970s...

, and Simon Croft's later one in C

C (programming language)

C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....

 under Unix

Unix

Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...

, and KRC was the main language used for teaching functional programming at the University of Kent

University of Kent

The University of Kent, previously the University of Kent at Canterbury, is a public research university based in Kent, United Kingdom...

 at Canterbury (UK) from 1982 to 1985.

The direct successor to KRC is Miranda

Miranda programming language

Miranda is a non-strict purely functional programming language designed by David Turner as a successor to his earlier programming languages SASL and KRC, using some concepts from ML and Hope. It was produced by Research Software Ltd...

, which includes a polymorphic type discipline based on that of Milner's ML

ML programming language

ML is a general-purpose functional programming language developed by Robin Milner and others in the early 1970s at the University of Edinburgh, whose syntax is inspired by ISWIM...

.

Further reading

• Functional Programming and its Applications, David A. Turner, Cambridge U Press 1982.