IA010: Principles of Programming Languages
Introduction
Achim Blumensath
blumens@fi.muni.cz
Faculty of Informatics, Masaryk University, Brno
Warm-up: A Quiz
What does this program do?
++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++
..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.
Warm-up: A Quiz
What does this program do?
++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++
..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.
Prints“Hello World!”
Warm-up: A Quiz
What does this program do?
++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++
..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.
Prints“Hello World!”
Brainfuck (1993)
▸ Turing-complete programming language
▸ tape containing numbers (inc/dec), a data pointer (l/r),
input/output, conditional jump
▸ compiler of size 100 bytes known to exist
Before high-level programming languages …
Now …
C
C++
Java
C#
Ada
Python
PHP
JavaScript
VisualBasic
Perl
Haskell
OCaml
F#
Scheme
…
Scala
Rust
Go
Swift
Now …
C
C++
Java
C#
Ada
Python
PHP
JavaScript
VisualBasic
Perl
Haskell
OCaml
F#
Scheme
…
Scala
Rust
Go
Swift
A zoo of programming languages
Now …
C
C++
Java
C#
Ada
Python
PHP
JavaScript
VisualBasic
Perl
Haskell
OCaml
F#
Scheme
…
Scala
Rust
Go
Swift
A zoo of programming languages
Can we somehow categorise them?
How do we choose one?
Profanity is the one language all programmers know best.
Anon.
Language popularity
TIOBE index, January 2017, www.tiobe.com
Language popularity
Desirable language features
Desirable language features
▸ simplicity
▸ orthogonality
▸ clear (and defined)
semantics
▸ ease of use
▸ easy to learn
▸ clean and readable syntax
▸ expressive power
▸ support for many paradigms
and coding styles
▸ strong safety guarantees
▸ produces fast code
▸ compilation speed
▸ reduced memory usage
▸ good library and tool chain
support
▸ standardisation and
documentation
▸ interoperability with other
languages
▸ hardware and system
independence
▸ support for hardware and
system programming
▸ usability by
non-programmers
▸ …
Kinds of software
Kinds of software
▸ business applications
▸ office software, graphics software
▸ server software
▸ video games
▸ number crunching
▸ phone apps
▸ control software for embedded devices
▸ scripts, utilities
Programming paradigms
Programming paradigms
▸ procedural: program is structured as a collection of
procedures/functions
▸ imperative: list of commands
▸ functional: expressions that compute a value
▸ declarative: describe what you want to compute, not how
▸ object-oriented: objects communicating via messages
▸ data-oriented: layout of your data in memory
▸ reactive: network of components that react to events
Which language/paradigm/coding style is the best?
Which language/paradigm/coding style is the best?
Choose the right tools for the job!
Which language/paradigm/coding style is the best?
Choose the right tools for the job!
⇒ the more tools available, the better
Which language/paradigm/coding style is the best?
Choose the right tools for the job!
⇒ the more tools available, the better
⇒ need to be familiar with many styles and paradigms
Which language/paradigm/coding style is the best?
Choose the right tools for the job!
⇒ the more tools available, the better
⇒ need to be familiar with many styles and paradigms
Multi-paradigm languages
The more paradigms your language support, the more tools you have
in your toolbox.
State of the art
▸ functional programming, dependent types: Idris
▸ linear types, borrow checker: Rust
▸ imperative programming, error handling: Zig
▸ imperative programming, design by contract: Dafny,Whiley
▸ module system: SML, Ocaml
▸ declarative programming: Mercury
▸ object-oriented programming: Scala
▸ concurrency: Go, Pony
(list somewhat biased and certainly incomplete)
Why study programming languages and paradigms?
The study of language features and programming styles helps you to
▸ choose a language most appropriate for a given task
▸ think about problems in new ways
▸ learn new ways to express your ideas and structure your code
(⇒ more tools in your toolbox)
▸ read other peoples code
▸ learn new languages faster (you only need to learn a new syntax)
▸ understand the design/implementation decisions and limitations
of a given language, so you can use it better:
▸ You can choose between alternative ways of expressing things.
▸ You understand more obscure features.
▸ You can simulate features not available in this particular
language.
Aspects of programming languages
Syntax the structure of programs.
Describes how the various constructs (statements, expressions, …) can
be combined into well-formed programs.
Semantics the meaning of programs.
Tells us what behaviour we can expect from a program.
Pragmatics the use of programming languages.
In which way is the language intended to be used in practice?
What are the various language constructions good for?
Aspects of programming languages
Syntax the structure of programs.
Describes how the various constructs (statements, expressions, …) can
be combined into well-formed programs.
PA008 Compiler Construction, PA037 Compiler Project,
IB005/IA006 Formal Languages
Semantics the meaning of programs.
Tells us what behaviour we can expect from a program.
IA011 Programming Language Semantics, IA014 Advanced Functional Programming
Pragmatics the use of programming languages.
In which way is the language intended to be used in practice?
What are the various language constructions good for?
this course
Course organisation
Lectures
▸ Wednesday, 16:00, A318
▸ language: English
▸ slides, lecture notes, and source code can be found in IS
▸ video recordings will also be made available there
Examination
▸ final written exam, in English
▸ k and z completion possible
Prerequisites
▸ no formal requirements
▸ knowledge of at least one programming language
▸ some basic knowledge of H������ helpful
▸ the more languages you know the better
Study materials
Books (only somewhat relevant)
▸ P. V. Roy, S. Haridi, Concepts, Techniques, and Models of
Computer Programming, 1st ed., MIT Press, 2004.
▸ R.W. Sebesta, Concepts of Programming Languages, 10th ed.,
Addison-Wesley, 2012.
▸ Programming language pragmatics, (Ed. M. L. Scott) 3rd ed.
Oxford, Elsevier Science, 2009.
Topics covered
▸ a brief history of programming languages
▸ expressions and functions
▸ types, type checking, type inference
▸ state and side-effects
▸ modules
▸ control-flow
▸ declarative programming
▸ object-oriented programming
▸ concurrency