Also: I know there are several modern computer languages that use arrows to represent anonymous functions (JS, Kotlin, Scala...).
I also personally remember using (and teaching) Maple in the mid-90s, which used arrows to define functions: https://www.maplesoft.com/support/help/Maple/view.aspx?path=operators/functional I used to find it perfectly natural. (There is obviously a fundamental difference here: Maple's functions are symbolic, while Python's are procedural. Maple also has procedures which can't be manipulated symbolically). S. On Tue, Feb 23, 2021 at 10:57 AM Stéfane Fermigier <s...@fermigier.com> wrote: > Hi, > > My personal opinion is that arrows or even fat arrows would be a nice > addition to the Python language for anonymous functions. > > I cringe a bit every time I have to write "lambda x: ..." (and even more > for parameter-less "lambda: ..."). > > I have a background in math so I find arrow notation very natural. I have > studied a bit lambda calculus, so I can relate to a notation inspired by it > too, but I believe: > > 1) That for it to be elegant, it should be more concise e.g. "ƛx: .." not > "lambda x: ..." (but Python is not APL and I don't believe we are ready to > introduce non-ascii unicode notations in the language). > > 2) More importantly, I believe most people are more familiar with the > arrow notation than the lambda notation (lambda calculus is, AFAIK, only > taught in advanced logic or CS courses at the University). > > S. > > > > On Tue, Feb 23, 2021 at 10:26 AM Steven D'Aprano <st...@pearwood.info> > wrote: > >> On Mon, Feb 15, 2021 at 09:29:45AM -0800, Guido van Rossum wrote: >> >> > Proposals like this always baffle me. Python already has both anonymous >> and >> > named functions. They are spelled with 'lambda' and 'def', respectively. >> > What good would it do us to create an alternate spelling for 'def'? >> [...] >> >> >> I think that the desire probably comes from thinking of short >> mathematical functions where the body is a simple expression, like in >> maths: >> >> def f(x): >> return 3*(x**2) - 2*x + 4 >> >> is kinda clunky and not very maths-like compared to: >> >> f(x) -> 3*(x**2) - 2*x + 4 >> >> which is suggestive of function notation: >> >> f : ℝ -> ℝ, f(x) = 3*(x**2) - 2*x + 4 >> >> If you've used modern Computer Algebra System calculators, they often >> have similar notation: >> >> # Texas Instruments Nspire >> 3⋅x² − 2⋅x + 4 -> y >> >> (except they have a proper arrow too, not just ASCII hyphen greater >> than). >> >> So there is definitely some aesthetic advantage to the arrow if you're >> used to maths notation, and if Python had it, I'd use it. >> >> But it doesn't scale up to multi-statement functions, and doesn't bring >> any new functionality into the language, so I'm not convinced that >> its worth adding as a mere synonym for def or lambda or both. >> >> >> -- >> Steve >> _______________________________________________ >> Python-ideas mailing list -- python-ideas@python.org >> To unsubscribe send an email to python-ideas-le...@python.org >> https://mail.python.org/mailman3/lists/python-ideas.python.org/ >> Message archived at >> https://mail.python.org/archives/list/python-ideas@python.org/message/SIY32PZLEPFLRPHWHT5FI3LCJGBXNNTB/ >> Code of Conduct: http://python.org/psf/codeofconduct/ >> > > > -- > Stefane Fermigier - http://fermigier.com/ - http://twitter.com/sfermigier > - http://linkedin.com/in/sfermigier > Founder & CEO, Abilian - Enterprise Social Software - > http://www.abilian.com/ > Chairman, National Council for Free & Open Source Software (CNLL) - > http://cnll.fr/ > Founder & Organiser, PyParis & PyData Paris - http://pyparis.org/ & > http://pydata.fr/ > -- Stefane Fermigier - http://fermigier.com/ - http://twitter.com/sfermigier - http://linkedin.com/in/sfermigier Founder & CEO, Abilian - Enterprise Social Software - http://www.abilian.com/ Chairman, National Council for Free & Open Source Software (CNLL) - http://cnll.fr/ Founder & Organiser, PyParis & PyData Paris - http://pyparis.org/ & http://pydata.fr/
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