# Functional and Logic programming

DF22100, 2010HT

Status Archive National Graduate School in Computer Science (CUGS) TCSLAB Wlodzimierz Drabent http://www.ida.liu.se/~wlodr/phd.lp/

 Course is separated in two parts: Functional Programming, vt10 Logic Programming, ht10

## Course plan

30 h

#### Recommended for

PdD students in computer science

a new course

#### Goals

Provide a solid introduction into the paradigms of logic programming and functional programming.

The course presents two programming paradigms, which differ from that of mainstream programming (i.e. procedural and object oriented). The latter can be seen as still related to the architecture of computer hardware. Its main concept - a mutable variable - is an abstraction of a RAM memory cell. In such languages, roughly speaking, programs are descriptions of sequences of computational steps. The role of the steps is to modify the state.
In contrast, programs in (pure) logic or functional programming describe the tasks of the computations. There is no state and mutable data; this makes it easy to reason about complex programs.

Logic programming (LP) employs (a subset of) the language of the standard first order logic as a programming language. In principle, a program is a set of axioms describing a problem to be solved; the computed results are logical consequences of the program. In practice, programs also describe how the results are computed; this can be modified by the programmer without changing the logical meaning of the program.
Hence reasoning about the meaning of programs and their correctness (declarative semantics) can be separated from that about program execution (operational semantics). Efficient implementations of LP exist.

Functional programming (FP) is a programming paradigm where the central
abstraction mechanism is a function.
FP has solid mathematical foundations. Many elegant programming techniques are specific for FP.
Compilers for modern functional languages, such as Haskell, OCaml and F#, can today both generate highly efficient code and discover many programming errors at compile time. FP has in the last decades mostly been used in academia, but has lately gained an increasingly interest within industry (e.g. Erlang and F#).

#### Prerequisites

Some mathematical maturity, for instance given by introductory courses on discrete mathematics, formal languages and automata theory, and logic.
Some experience of programming; familiarity with some programming languages.

#### Organization

Lectures.
Exercises and project work.

#### Contents

[subject to modifications]

Logic Programming (LP)
- Definite clause logic programs, their declarative and operational semantics.
- Prolog as an implementation of LP.
- Programming examples, LP as a declarative programming paradigm.
- Negation in LP, including Answer Set Programming.
- Reasoning about logic programs (formal & practical).
- Extensions of "classical" LP. Constraint logic programming.

Functional Programming (FP)
Central concepts such as higher-order functions, pattern matching, dynamic vs. static type checking, referential transparency, type inference, parametric polymorphism, eager vs. lazy evaluation, tail-recursion, type classes, and monads.
FP relation to lambda-calculus.
Focus on statically typed functional programming languages, e.g. OCaml and Haskell.

#### Literature

Articles, handouts, book chapters.
U. Nilsson and J. Maluszynski. Logic, Programming and Prolog (2ed).

#### Lecturers

P. Fritzson
W. Drabent
Guest lectures and FP lab assistants:
David Broman (Strict FP, OCAML)

P. Fritzson (FP)
W. Drabent (LP)

#### Examination

Home assignments and a minor project.

#### Credit

5hp maximally for the Functional Programming part (spring).
5hp maximally for the Logic Programming part (autumn).