Pharo

For other uses, see Pharo (disambiguation).

Not to be confused with the similar term Pharaoh (disambiguation).

Pharo

Pharo logo with lighthouse
Paradigm	object-oriented
Family	Smalltalk: Squeak
Developer	Pharo community
First appeared	March 2008; 16 years ago (2008-03)
Stable release	12.0[1]  / 26 April 2024; 8 months ago (26 April 2024)
Typing discipline	dynamic
Implementation language	Smalltalk
Platform	ARM, IA-32, x86-64
OS	Windows, Linux, macOS, others
License	MIT, partly Apache 2.0[2]
Website	pharo.org
Influenced by
Smalltalk (Squeak)

Pharo is a cross-platform implementation of the classic Smalltalk-80 programming language and runtime system.^[3] It is based on the OpenSmalltalk virtual machine (VM) named Cog,^{[4][5][6][7]: 16} which evaluates a dynamic, reflective, and object-oriented programming language with a syntax closely resembling Smalltalk-80. It is free and open-source software, released under a mix of MIT, and Apache 2 licenses.

Pharo is shipped with source code compiled into a system image that contains all software needed to run Pharo.^[7]: 16 Like the original Smalltalk-80, Pharo provides several live programming features such as immediate object manipulation, live updates, and just-in-time compilation (JIT). The system image includes an integrated development environment (IDE) to modify its components.

Pharo was forked from Squeak v3.9 in March of 2008.^{[8][3][7][7]: 10 [9]}

Overview

Pharo is a pure object-oriented, dynamically typed, and reflective language. The stated project goal is to revisit Smalltalk design and enhance it.

The name Pharo comes from the French word "phare" (French pronunciation: [faʁ]) which means lighthouse. This is why the Pharo logo shows a drawing of a lighthouse inside the final letter O of the name.

Key features

Virtual machine

• Multiplatform virtual machine with just-in-time compilation (JIT), combined generational garbage collector, ephemerons, forwarders
• Fast object enumeration
• Easy call stack manipulation
• AST metalinks
• Relatively low memory consumption
• Customizable compiler
• Optional complete object memory persistence
• Resumable exceptions
• Fast object serialization

Built-in software

• Optional fusion of developed program and development environment
• Live object inspection

Language features

• Simple syntax
• Object-oriented programming
• Immediate object identity swapping
• Dynamic inheritance
• Objects as methods
• Optional Green threads
• Customizable metaclasses
• Easy to use proxy objects

Relation to Smalltalk

Pharo is based on general concepts of Smalltalk but seeks to improve on them, so does not limit itself to them. The basic syntax of the language has a close resemblance to Smalltalk. However, the way classes are defined in Pharo differs from other Smalltalk dialects.^[how?]

Language syntax

Pharo syntax postcard

The Pharo syntax is based on Smalltalk-80 language syntax with several extensions. Some of these are common among modern Smalltalk dialects.

• literals for dynamic arrays. The expressions that specify the array content are evaluated during program execution

{1. 2. 1+2}

• literals for byte arrays that can be composed only of integer numbers in the range from 0 to 255

#[1 2 3 4]

• literals for scaled decimals, a representation of fixed point decimal numbers able to accurately represent decimal fractions

3.14s2

• pragmas. In Smalltalk-80 the pragmas are used only for primitive methods. In Pharo they are fully capable method annotations

<gtInspectorPresentationOrder: 30>

• two double quotes inside a comment are interpreted as one double quote character that is part of the content of the comment

The Pharo language syntax is supposed to be very simple and minimalist. The basic language elements are often presented on one postcard as a showcase for the language's brevity. The grammar is classified as LL(1).

The language grammar does not specify directly how the code should be stored in files. Pharo uses Tonel as the preferred code serializing format.

History

Pharo emerged as a fork of Squeak, an open-source Smalltalk environment created by the original Smalltalk-80 team (Dan Ingalls and Alan Kay). Pharo was created by S. Ducasse [1] and M. Denker in March 2008. It focuses on modern software engineering and development techniques.^{[citation needed]} Pharo is supported by the Pharo consortium (for legal entities) [2] and the Pharo association for physical persons [3].

Pharo version	Release date	Major features
	March 16, 2008[10]	Fork of Squeak environment
1.0	April 15, 2010	real closures, EToys and MVC removed
1.1	July 26, 2010	Cog JIT VM, Settings framework
1.2	March 29, 2011	new Finder, Recent changes tool, improved Help, better themes
1.3	August 2011	Zinc, headless images
1.4	April 2012[11]	Ring metamodel, better code simulator
2.0	March 18, 2013[12]	browser improvements, QA tools, Fuel serializer, better files API
3.0	April 2014[13]	new modular compiler (Opal) and debugger, continuations
4.0	April 2015[14]	GTools, slots
5.0	May 2016[15]	Spur VM, UFFI, improved reflectivity
6.0	6 June, 2017[16]	64-bit and Git support
6.1	24 July, 2017[17]	improved Git support
7.0	22 January, 2019[18]	bootstrapping, new code browser (Calypso), stateful traits
8.0	20 January, 2020[19]	improved support of Git, testing, refactoring and Windows
9.0	15 July, 2021[20]	GTK3 support, object-centric debugger and inspector, refactorings, official ARM VMs
10.0	5 April, 2022[21]	Cleanups, modularization, many rewritten and improved tools
11.0	11 May, 2023[22]	Ephemerons, SIMD, more efficient closures, improved tools
Current stable version: 12.0	26 May, 2024[23]	New debug points system, new class definitions, permanent space

Use of Pharo

Companies and consultants

Some companies use Pharo for their development projects.^[24] In particular, they use:

• Seaside for dynamic web development^[25]
• Zinc for server architectures^[26]
• Moose^[27] to analyse data and software from all programming languages
• Graphic libraries for evolved user interfaces
• Roassal to visualize data^[28]

The Pharo consortium^[29] was created for companies wishing to support the Pharo project. The Pharo association^[30] was created in 2011^[31] for users wishing to support the project.

Performance and virtual machine (VM)

Pharo relies on a virtual machine that is written almost entirely in Smalltalk. Beginning in 2008, a new virtual machine (Cog) for Squeak, Pharo and Newspeak has been developed that performs nearly as well as the fastest Smalltalk virtual machine.^[32] In 2014/2015 the VM community is working on Spur, a new Memory Manager for Cog that should again increase performance and provide better 64-bit VM support.^[33]

See also

• Amber Smalltalk
• GNU Smalltalk
• Squeak
• VisualWorks

References

1. https://pharo.org/news/2024-04-26-pharo12-released.html. {{cite web}}: Missing or empty |title= (help)
2. Pharo license information
3. Black, Andrew P.; Ducasse, Stéphane; Nierstrasz, Oscar; Pollet, Damien; Cassou, Damien; Denker, Marcus (October 28, 2009). Pharo by example. Kehrsatz, Switzerland. ISBN 978-3-9523341-4-0. OCLC 957555627.
4. "OpenSmalltalk". opensmalltalk.org. Retrieved November 24, 2021.
5. OpenSmalltalk/opensmalltalk-vm, OpenSmalltalk, November 23, 2021, retrieved November 24, 2021
6. "Cog Blog: About Cog". Retrieved November 24, 2021.
7. Black, Andrew P.; Ducasse, Stéphane; Nierstrasz, Oscar; Pollet, Damien (October 28, 2009). Pharo by Example. Samuel Morello. Lulu.com. ISBN 978-3-9523341-4-0.
8. "DevelopOnTheWeb". developontheweb.co.uk. Retrieved November 24, 2021.
9. "The Rise and Fall of Commercial Smalltalk". www.wirfs-brock.com. Retrieved November 24, 2021.
10. "Pharo got 10 years". Pharo-project.org. May 29, 2018. Retrieved May 31, 2018.
11. "Pharo Open Source Smalltalk — Release 1.4". Pharo-project.org. April 17, 2012. Retrieved April 5, 2013.
12. "Pharo Open Source Smalltalk — Release 2.0". Pharo-project.org. March 18, 2013. Retrieved April 5, 2013.
13. "Pharo Open Source Smalltalk — Release 3.0". pharo.org. April 30, 2014. Archived from the original on August 23, 2017. Retrieved May 1, 2014.
14. "Pharo Open Source Smalltalk — Release 4.0". pharo.org. April 15, 2015. Archived from the original on August 23, 2017. Retrieved April 16, 2015.
15. "Pharo Open Source Smalltalk — Release 5.0". pharo.org. May 12, 2016. Archived from the original on December 29, 2017. Retrieved May 13, 2016.
16. "Pharo Open Source Smalltalk - Release 6.0". pharo.org. June 6, 2017. Archived from the original on November 20, 2017. Retrieved June 6, 2017.
17. "Pharo 6.1 released". pharo.org. July 24, 2017. Archived from the original on August 20, 2017. Retrieved August 11, 2017.
18. "Pharo 7.0 released". pharo.org. January 22, 2019. Archived from the original on February 12, 2022. Retrieved January 22, 2019.
19. "Pharo 8.0 Released!". pharo.org. January 20, 2020. Archived from the original on February 12, 2022. Retrieved January 20, 2020.
20. "Pharo 9.0 Released!". pharo.org. July 15, 2021.
21. "Pharo 10.0 Released!". pharo.org. April 5, 2022.
22. "Pharo 11.0 Released!". pharo.org. May 11, 2023.
23. "Pharo 12.0 Released!". pharo.org. May 26, 2024.
24. "Pharo Open Source Smalltalk — Success stories" (Press release). Pharo-project.org. Retrieved April 5, 2013.
25. "Home". seaside.st. March 18, 2007. Retrieved April 5, 2013.
26. "Zinc HTTP Components". Zn.stfx.eu. Retrieved April 5, 2013.
27. Girba, Tudor. "Home". Moose technology. Retrieved April 5, 2013.
28. "Agile Visualization". Object Profile. Retrieved May 31, 2018.
29. "web: Pharo Consortium". Consortium.pharo.org. March 31, 2013. Retrieved April 5, 2013.
30. Ducasse, Stephane. "association: Pharo Association". Association.pharo.org. Retrieved April 5, 2013.
31. "Annonce JOAFE n°1025 de la parution n°20110013 du 26 mars 2011". Journal-officiel.gouv.fr. Retrieved May 1, 2022.
32. "Cog Blog". Mirandabanda.org. Retrieved April 5, 2013.
33. "7-point summary of the Spur memory manager". Clément Béra. February 6, 2014. Retrieved April 17, 2015.

External links

• Official website