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?
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
▸ Thursday, 16:00, A217
▸ 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 Haskell 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.
Additional resources
▸ Crafting Interpreters, www.craftinginterpreters.com
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