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Line 1: {{Short description\|Audio programming language}} {{No footnotes\|date=March 2015}}▼ {{redirect\|FAUST\|other uses\|Faust (disambiguation){{!}}Faust}} ▲{{NoMore footnotes needed\|date=March 2015}} {{Infobox software \| name = FAUST \| developer = GRAME, Centre National de Création Musicale \| author = Yann Orlarey, Dominique Fober, Stéphane Letz \| released = {{~~release~~start date\|2002}} \| latest release version = 02.960.~~100~~3<ref>[https://github.com/grame-cncm/faust/releases Releases · grame-cncm/faust · GitHub]</ref> \| latest release date = {{~~release~~start date\|~~2017~~2023\|06\|14}} \| operating system = [[Linux]], [[OS X]], [[Microsoft Windows\|Windows]], [[Unix]] \| genre = Functional programming language for audio signal processing \| repo = {{URL\|https://github.com/grame-cncm/faust/}} \| programming language = [[C++]] \| license = [[GNU General Public License\|GPL]] \| website = {{URL\|faust.grame.fr}} }} {{Portal\|Free and open-source software}} '''FAUST''' (Functional AUdio STream) is a [[~~Domain~~ ___domain-specific language\|___domain-specific]] [[~~Purely~~purely functional programming\|purely functional]] [[programming language]] for implementing [[signal processing]] [[algorithms]] in the form of [[Library (computing)\|libraries]], [[audio plug-ins]], or standalone applications. A FAUST program denotes a signal processor: a mathematical function that is applied to some input signal and then fed out. ==Overview== The FAUST [[programming model]] combines a [[functional programming]] approach with a [[block diagram]] syntax: * The functional programming approach provides a natural framework for [[signal processing]]. Digital signals are modeled as [[Sequence\|discrete functions]] of time, signal processors as [[Higher-order function\|second order functions]] that operate on them, and ~~FAUST’s~~FAUST's block diagram ''composition operators'', used to combine signal processors together, as third order functions, etc. * Block diagrams, even if purely textual as in FAUST, promote a modular approach to signal processing that complies with sound engineers' and audio developers' habits. A FAUST program ~~doesn’t~~doesn't describe a sound or a group of sounds, but a [[Digital signal processing\|signal processor]]. The program source is organized as a set of ''definitions'' with at least the definition of the keyword <code>process</code> (the equivalent of <code>main</code> in C): <~~source~~syntaxhighlight lang=haskell> process = ...; </syntaxhighlight> ~~</source>~~ The FAUST [[compiler]] translates FAUST code into a [[C++]] [[Object-oriented programming\|object]], which may then interface with other C++ code to produce a full program. Line 35 ⟶ 38: ==Example code== FAUST programs define a <code>process</code> function that operates on incoming data. This is analogous to the <code>main</code> function in most programming languages. The following is an example that produces silence: <~~source~~syntaxhighlight lang="haskell"> process = 0; </syntaxhighlight> ~~</source>~~ The second example copies the input signal to the output. It involves the <code>_</code> primitive that denotes the [[identity function]] for signals: <~~source~~syntaxhighlight lang="haskell"> process = _; </syntaxhighlight> ~~</source>~~ Another example sums a stereo signal into a mono signal using the <code>+</code> primitive: <~~source~~syntaxhighlight lang="haskell"> process = +; </syntaxhighlight> ~~</source>~~ [[File:Faust-simple-block-diagram.jpg\|thumb\|Block diagrams generated by Faust from some simple programs]] Most FAUST primitives are analogous to their C counterpart on numbers, but lifted to signals. For example, the FAUST primitive <code>sin</code> operates on a signal X by applying the [[C (programming language)\|C]] function <code>sin</code> to each sample X[t]. All C numerical functions have their counterpart in FAUST. Some [[signal processing]] primitives are specific to FAUST. For example, the delay operator <code>@</code> takes two input signals: X (the signal to be delayed) and D (the delay to be applied), and produces an output signal Y such that Y(t) = X(t − D(t)). ==Block diagram composition== Line 69 ⟶ 72: Using the sequential composition operator <code>:</code> the output of <code>+</code> can be routed to the input of <code>abs</code> to compute the [[absolute value]] of the signal: <~~source~~syntaxhighlight lang="haskell"> process = + : abs; </syntaxhighlight> ~~</source>~~ Here is an example of parallel composition using the <code>,</code> operator that arranges its left and right expressions in parallel. This is analogous to a stereo cable. <~~source~~syntaxhighlight lang="haskell"> process = _,_; </syntaxhighlight> ~~</source>~~ These operators can be ~~arbitrarily~~ combined arbitrarily. The following code multiplies an input signal with 0.5: <~~source~~syntaxhighlight lang="haskell"> process = _,0.5 : ; </syntaxhighlight> ~~</source>~~ The above may be rewritten in [[currying\|curried]] form: <~~source~~syntaxhighlight lang="haskell"> process = (0.5); </syntaxhighlight> ~~</source>~~ The recursive composition operator <code>~</code> can be used to create block diagrams with cycles (that include an implicit one-sample delay). Here is an example of an integrator that takes an input signal X and computes an output signal Y such that Y(t) = X(t) + Y(t−1): <~~source~~syntaxhighlight lang=haskell> process = + ~ _; </syntaxhighlight> ~~</source>~~ ==Generating full applications== Using specific ''architecture files'', a FAUST program can be used to produce code for a variety of platforms and plug-in formats. These architecture files act as wrappers and describe the interactions with the host audio and GUI system. {{As of\|~~2015~~2021}}, more than 1030 architectures are supported and new ones may be implemented by anyone. [[File:Faust-mixer-jackqt.jpg\|thumb\|Screenshot of mixer.dsp (available in the FAUST distribution) using the jack-qt architecture]] Line 96 ⟶ 99: {\| class="wikitable" \|+ Some architecture files available for FAUST ! File \| alsa-gtk.cpp \|\| ALSA application + GTK▼ ! Architecture \|- \| alsa-qtgtk.cpp \|\| ALSA application + ~~QT4~~[[GTK]] \|- ▲\| alsa-~~gtk~~qt.cpp \|\| ALSA application + ~~GTK~~[[Qt (software)\|Qt]] 4 \|- \| android.cpp \|\| Android applications Line 104 ⟶ 110: \| au.cpp \|\| Audio Unit plug-in \|- \| ca-qt.cpp \|\| CoreAudio application + ~~QT4~~Qt 4 \|- \| ios-coreaudio.cpp \|\| iPhone and iPad applications Line 110 ⟶ 116: \| jack-gtk.cpp \|\| JACK application + GTK \|- \| jack-qt.cpp \|\| JACK application + ~~QT4~~Qt 4 \|- \| ladspa.cpp \|\| LADSPA plug-in Line 116 ⟶ 122: \| max-msp.cpp \|\| Max MSP plug-in \|- \| pd.cpp \|\| ~~Puredata~~Pure Data plug-in \|- \| q.cpp \|\| Q language plug-in \|- \| supercollider.cpp \|\| ~~Supercollider~~SuperCollider plug-in \|- \| vst.cpp \|\| VST plug-in Line 132 ⟶ 138: A useful option makes it possible to generate the block diagram representation of the program as one or more SVG graphic files. It is useful to note the difference between the block diagram and the generated C++ code. As stated, the key idea here is not to compile the block diagram literally, but the mathematical function it denotes. Modern C/C++ compilers also ~~don’t~~don't compile programs literally. But because of the complex semantics of C/C++ (due to side effects, pointer aliasing, etc.) they ~~can’t~~can't go very far in that direction. This is a distinct advantage of a purely functional language: it allows compilers to do very advanced optimisations. ==Arrows-like semantics== Line 140 ⟶ 146: {\| class="wikitable" \|+ Equivalences between FAUST and Arrow combinators \| <code>f~g</code> \|\| <{{code>\|2=haskell\|1=loop ((\(a,b) -> (b,a)) ^>> f >>> id &&& (delay>>>g))~~</code>~~}} where <code>delay</code> is not a method of the <code>Arrow</code> type class, but is specific to signal processing arrows \|- \| <code>f,g</code> \|\| <code>f**g</code> Line 191 ⟶ 197: \| year = 2011 }} {{cite journal \|first1=Pierre \|last1=Jouvelot Line 197 ⟶ 203: \|last2=Orlarey \|title=Dependent Vector Types for Data Structuring in Multirate Faust \|journal=Computer Languages, Systems ~~and~~& Structures~~ – Elsevier~~ \|url=http://faust.grame.fr/images/faust-doc/papers/faust-elsevier2011.pdf \|year=2011 \|volume=37 }}{{dead link\|date=December 2016 \|bot=InternetArchiveBot \|fix-attempted=yes }}▼ \|issue=3 \|pages=113–131 \|doi=10.1016/j.cl.2011.03.001 ▲ }}{{dead link\|date=December 2016 \|bot=InternetArchiveBot \|fix-attempted=yes }} * {{Cite web \| first = Julius O. Line 208 ⟶ 218: \| year = 2011 }} * {{cite journal \|first3=Dominique \|last3=Fober Line 219 ⟶ 229: \|url=http://faust.grame.fr/images/faust-doc/papers/faust-CFA-2010.pdf \|year=2010 }}{{dead link\|date=December 2016 \|bot=InternetArchiveBot \|fix-attempted=yes }} * {{cite journal \| first3 = Dominique Line 241 ⟶ 251: \| year = 2010 }} * {{cite journal \|first1=Jérôme \|last1=Barthélemy Line 259 ⟶ 269: \|pages=369–372 \|year=2010 }}{{dead link\|date=December 2016 \|bot=InternetArchiveBot \|fix-attempted=yes }} * {{cite journal \| first1 = Pierre Line 266 ⟶ 276: \| last2 = Orlarey \| title = Depandant Vector Types for Multirate Faust \| journal = Proceedings of the 7th Sound anand Music Computing Conference (SMC-2010) \| url = http://smcnetwork.org/files/proceedings/2010/51.pdf \| pages = 345–352 \| year = 2010 \| access-date = 2011-10-11 \| archive-url = https://web.archive.org/web/20120407043121/http://smcnetwork.org/files/proceedings/2010/51.pdf \| archive-date = 2012-04-07 \| url-status = dead }} * {{cite journal \|first3=Dominique \|last3=Fober Line 282 ⟶ 296: \|url=http://faust.grame.fr/test/images/faust-doc/papers/faustLAC09.pdf \|year=2009 }}{{dead link\|date=December 2016 \|bot=InternetArchiveBot \|fix-attempted=yes }} * {{cite book \| first1 = Pierre Line 292 ⟶ 306: \| url = http://faust.grame.fr/images/faust-doc/papers/multirate-faust.pdf \| year = 2009 }}{{Dead link\|date=December 2019 \|bot=InternetArchiveBot \|fix-attempted=yes }} }} * {{cite journal \| first2 = Dominique Line 303 ⟶ 317: \| url = http://smc2009.smcnetwork.org/programme/pdfs/232.pdf \| year = 2009 \| archive-date = 2012-04-25 \| access-date = 2011-10-11 \| archive-url = https://web.archive.org/web/20120425061241/http://smc2009.smcnetwork.org/programme/pdfs/232.pdf \| url-status = dead }} * {{cite book Line 317 ⟶ 335: \| isbn = 978-2-7521-0054-2 \| year = 2009 }}{{Dead link\|date=December 2019 \|bot=InternetArchiveBot \|fix-attempted=yes }} }} * {{cite journal \|first3=Dominique \|last3=Fober Line 329 ⟶ 347: \|url=http://faust.grame.fr/images/faust-doc/papers/jack-faust-multicore.pdf \|year=2008 }}{{dead link\|date=December 2016 \|bot=InternetArchiveBot \|fix-attempted=yes }} * {{cite journal \| first = Albert Line 343 ⟶ 361: \| last = Smith III \| title = Introduction to Digital Filters: With Audio Applications \| chapter = Appendix K. Digital Filtering in Faust and PD \| publisher = W3K Publishing \| year = 2007 \| isbn = 978-0-9745607-1-7 \| chapter-url = https://books.google.com/books?id=pC1iCQUAsHEC&pg=PA417 \| pages = ~~417-~~417–? }} * {{cite journal Line 386 ⟶ 404: \| publisher = Computer Music Association \| url = http://quod.lib.umich.edu/cgi/t/text/text-idx?c=icmc;idno=bbp2372.2005.* \| ~~chapterurl~~chapter-url = http://quod.lib.umich.edu/i/icmc/bbp2372.2005.054?view=image \| year = 2005 \| page = 286 Line 401 ⟶ 419: \| url = http://faust.grame.fr/images/faust-doc/papers/faust-soft-computing.pdf \| year = 2004 }}{{Dead link\|date=December 2019 \|bot=InternetArchiveBot \|fix-attempted=yes }} }} * {{cite journal \|first1=Nicolas \|last1=Scaringella Line 413 ⟶ 431: \|url=http://faust.grame.fr/images/faust-doc/papers/JIM2003vect.pdf \|year=2003 }}{{dead link\|date=December 2016 \|bot=InternetArchiveBot \|fix-attempted=yes }} * {{cite journal \|first3=Stéphane \|last3=Letz Line 425 ⟶ 443: \|url=http://faust.grame.fr/images/faust-doc/papers/faust-jim2002.pdf \|year=2002 }}{{dead link\|date=December 2016 \|bot=InternetArchiveBot \|fix-attempted=yes }} * {{cite journal \|first3=Stéphane \|last3=Letz Line 437 ⟶ 455: \|url=http://faust.grame.fr/images/faust-doc/papers/faust-icmc2002.pdf \|year=2002 }}{{dead link\|date=December 2016 \|bot=InternetArchiveBot \|fix-attempted=yes }} {{Refend}} Line 443 ⟶ 461: {{Commons category\|FAUST (programming language)}} * {{Official website\|faust.grame.fr}}, online compiler, support, documentation, news, etc. * {{GitHub\|grame-cncm/faust}} * [https://sourceforge.net/projects/faudiostream/ FAUST on SourceForge]: Faust repository and mailing lists [[Category:Audio programming languages]] [[Category:Programming languages created in 2002]]