[Edu-sig] the string type (was: making types matter (notes for beginners))

[Wes Turner]

u"Unicode 💓"
r"raw string"
f"f-{string}"

>From https://docs.python.org/3/howto/unicode.html :

>>> "\N{GREEK CAPITAL LETTER DELTA}"  # Using the character name
'\u0394'
>>> "\u0394"                          # Using a 16-bit hex value
'\u0394'
>>> "\U00000394"                      # Using a 32-bit hex value
'\u0394'

... The u is silent (and optional).

On Tuesday, January 29, 2019, Wes Turner <wes.turner at gmail.com> wrote:

>
>
> On Tuesday, January 29, 2019, kirby urner <kirby.urner at gmail.com> wrote:
>
>>
>> Thanks Wes, especially for the URLs relating type theory to "HoTT" by way
>> category theory.
>>
>> My friend and co-podcaster Alex, a math-physics-philo guy, has been
>> pushing me to bone up in that area [1].  Those links really helped.
>>
>
> https://github.com/ejgallego/jscoq#homotopy-type-theory
>
> "[…] JsCoq/JsHoTT Interactive Online System!"
> https://x80.org/rhino-hott/
>
>
>>
>> I'm squeezing some of this in while reading the OSCON 2019 proposals, a
>> big job, but I always learn a lot by so doing. [2]
>>
>> When it comes to Beginner Python and types, people have a strong grasp of
>> number types coming in, especially ints, but think they know more about the
>> string type than they really do, thanks to the whole coding/decoding
>> business.
>>
>
> ints and types ... floordiv and div
>
> https://github.com/python/typeshed/blob/master/stdlib/2and3/operator.pyi
>
> > def truediv(a: Any, b: Any) -> Any: ...
> > def __truediv__(a: Any, b: Any) -> Any: ...
> > if sys.version_info < (3, ):
> >    def div(a: Any, b: Any) -> Any: ...
> >    def __div__(a: Any, b: Any) -> Any: ...
>
> def div(x: int, y: int) -> Union[float, int]: ...
>
> https://docs.python.org/3/library/operator.html#operator.floordiv
> >> 7 // 2
>
> https://docs.python.org/3/library/operator.html#operator.truediv
> >> 7 / 2
>
> >> assert sys.version_info.major < 3
> >> from __future__ import division
> >> 7 / 2
>
> And then there are fractions, and decimals, and arbitrary-precision floats
> https://github.com/python/typeshed/blob/master/stdlib/2and3/fractions.pyi
>
>
>> i.e. strings are always "encrypted" (encoded) a specific way, even if
>> only as plain ASCII text.  K-16 doesn't do a lot to introduce Unicode, even
>> though it's fundamental.  I'd teach Unicode in language arts, along with
>> fonts and old fashioned printing and book binding.
>>
>
> Is there a good resource for Unicode with something like the output from
> `hexdump -C`?
>
> With Python 3, Unicode emoji just work! :sandwich:
>
>
>>
>> What I find works well with kids and adults alike is a lot of emphasis on
>> Emoji, which are now a part of Unicode after all.  They're colorful and
>> ubiquitous in modern life.
>>
>> There's something satisfying about being able to have
>>
>> ["😉", "🐋", "🚂"]
>>
>> as a Python list.
>>
>> We can also use non-keyboard characters in identifiers, though emoji
>> won't work (there's no making your emojis callable in other words).
>>
>> *** testing 1-2-3... how did that list come through in the Mailman
>> archives? Displayed as Emoji, not as missing glyphs?  I see Wes already
>> used a yellow hand pointing down, so I'm confidant the glyphs should be
>> there ***
>>
>> Contemporary IDEs and web browsers are up to showing emoji.
>>
>
>> When you think about Unicode as a database with records (fields as
>> attributes) you realize that the string type alone is a huge door opener.
>> It's also about number bases and HTML entities.  Lots to know.
>>
>
> Strings and Unicode ....
>
> https://en.wikipedia.org/wiki/Executable_space_protection
> - What's executable code and what's </data>? Strings are often both, so we
> must consider where they'll be output; and we cannot trust user-supplied
> input to not contain executable code.
>
> https://en.wikipedia.org/wiki/String_literal#Escape_sequences
>
> https://en.wikipedia.org/wiki/Control_character
>
> https://en.wikipedia.org/wiki/Escape_sequence
>
> https://en.wikipedia.org/wiki/Cross-site_scripting#Preventive_measures
>
> https://en.wikipedia.org/wiki/Cross-site_scripting#Related_vulnerabilities
>
>
>
> import string
> print(dir(string))
> print(string.punctuation)
>
> ### https://en.wikipedia.org/wiki/Code_injection#Examples ##
>
> import cgi, http
> cgi.escape('''<a href="javascript:alert('hello')">here</a>''')
>
>
> # https://docs.python.org/3/library/urllib.parse.html#
> urllib.parse.quote_plus
> import urllib
> # urllib.parse.quote_plus
> # urllib.parse.unquote
>
>
> # https://bleach.readthedocs.io/en/latest/
> import bleach
> bleach.clean("...")
> bleach.urlify("...")
>
>
> https://en.wikipedia.org/wiki/ANSI_escape_code#Escape_sequences
> https://en.wikipedia.org/wiki/ANSI_escape_code#Colors
> https://github.com/urwid/urwid/blob/master/urwid/escape.py
>
> https://docs.python.org/3/library/shlex.html#shlex.quote
>
> ... There are a bunch of packages to add colors to text with Python. You
> can also just add raw escape *start* and end* character sequences to
> strings and print them out.
>
>
>>
>> About half of my students are middle schoolers [3], the other half are
>> adults [4].
>>
>> The Emoji (Unicode) stuff works at all levels.
>>
>> I notice the Rust docs are into it.
>>
>> Show your language is Unicode savvy that way, good PR.
>>
>> Kirby Urner
>> 4dsolutions.net
>> cascadia.or.pdx
>>
>> [1]
>> It's something of a joke how everyone starts a Monad tutorial the same
>> way, by decrying the dearth of coherent Monad tutorials, hah hah.
>>
>> The emphasis on composing functions in category theory takes me to this
>> decorator class, my Monad in progress:
>>
>> https://repl.it/@kurner/MakingMonads
>>
>> https://youtu.be/caSOTjr1z18  (functional programmer speaking to his
>> community)
>> https://youtu.be/SknxggwRPzU  (Dutch prof with several relevant
>> interviews on computerphile channel)
>> https://youtu.be/IOiZatlZtGU  (good overview of how logic and CS come
>> together over time, focus on lambda stuff).
>>
>
> functools, toolz.functoolz, fn.py:
>
> https://docs.python.org/3/library/functools.html#functools.partial
> https://docs.python.org/3/library/functools.html#functools.wraps (copies
> __doc__ strings over)
>
> https://toolz.readthedocs.io/en/latest/curry.html
> https://toolz.readthedocs.io/en/latest/_modules/toolz/functoolz.html
>
> https://github.com/kachayev/fn.py
> - #scala-style-lambdas-definition
> - https://github.com/kachayev/fn.py/blob/master/README.rst#
> high-level-operations-with-functions
>
> > The fn.py fn.monad.optionable decorator — @optionable — makes functional
> composition with chaining easy, too: https://github.com/kachayev/
> fn.py/blob/master/README.rst#functional-style-for-error-handling
>
>
>>
>> FYI, I've used "λ-calculus" (Church, Turing et al) to loosely brand an
>> alternative track through high school, that could in theory count with
>> future employers and colleges as much as today's prevelant "Δ-calculus"
>> (Newton-Leibniz).
>>
>> Here's how I use λ-calc in contrast with Δ-calc (against a STEM backdrop
>> -- I've since done more to map out PATH).
>> https://youtu.be/eTDH7m4vEiM
>>
>> I'm simply sharing a vision (heuristic, gestalt), akin to science
>> fiction, not proposing legislation nor composing any "thou shalt" edict --
>> so no need to get too political about it I'm hoping.  Food for thought.
>>
>> [2] a Medium story (be me) that gives a big picture broad brush stroke
>> history leading up to the resurrection of O'Caml, the language:
>> https://medium.com/@kirbyurner/stories-from-cyberia-fc857867e147
>>
>> [3]  middle school: next Coding with Kids gig starts tomorrow:
>> https://youtu.be/6qlj_AZqpto (a look at Codesters)
>>
>> [4]  adults: next SAISOFT gig starts in February:
>> https://github.com/4dsolutions/SAISOFT
>> (lots of Jupyter Notebooks; we also use Spyder and vs code, both with
>> Anaconda)
>>
>>
>>
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