[Python-ideas] allow `lambda' to be spelled λ

[Sven R. Kunze]

Completely matches my opinion. Thanks.

On 12.07.2016 20:36, tritium-list at sdamon.com wrote:
>
> For better or worse, except for string literals which can be anything 
> as long as you set a coding comment, python is pure ascii which 
> simplifies everything.  Lambda is not in the first 128 characters of 
> Unicode, so it is highly unlikely to be accepted.
>
> ·‘Lambda’ is exactly as discouraging to type as it needs to be.  A 
> more likely to be accepted alternate keyword is ‘whyareyounotusingdef’
>
> ·Python doesn’t attempt to look like mathematical formula
>
> ·‘Lambda’ spelling is intuitive to most people who program
>
> ·TIMTOWTDI isn’t a religious edict.  Python is more pragmatic than that.
>
> ·It’s hard to type in ALL editors unless your locale is set to 
> (ancient?) Greek.
>
> ·… What are you doing to have an identifier outside of 
> ‘[A-Za-z_][A-Za-z0-9_]+’?
>
> *From:*Python-ideas 
> [mailto:python-ideas-bounces+tritium-list=sdamon.com at python.org] *On 
> Behalf Of *Stephan Houben
> *Sent:* Tuesday, July 12, 2016 8:38 AM
> *To:* python-ideas at python.org
> *Subject:* [Python-ideas] allow `lambda' to be spelled λ
>
> Hi list,
>
> Here is my speculative language idea for Python:
>
> Allow the following alternative spelling of the keyword `lambda':
>
> λ
>
> (That is "Unicode Character 'GREEK SMALL LETTER LAMDA' (U+03BB).")
>
> Background:
>
> I have been using the Vim "conceal" functionality with a rule which 
> visually
>
> replaces lambda with λ when editing Python files. I find this a great 
> improvement in
>
> readability since λ is visually less distracting while still quite 
> distinctive.
>
> (The fact that λ is syntax-colored as a keyword also helps with this.)
>
> However, at the moment the nice syntax is lost when looking at the 
> file through another editor or viewer.
>
> Therefore I would really like this to be an official part of the 
> Python syntax.
>
> I know people have been clamoring for shorter lambda-syntax in the 
> past, I think this is
>
> a nice minimal extension.
>
> Example code:
>
>   lst.sort(key=lambda x: x.lookup_first_name())
>
>   lst.sort(key=λ x: x.lookup_first_name())
>
>   # Church numerals
>
>   zero = λ f: λ x: x
>
>   one = λ f: λ x: f(x)
>
>   two = λ f: λ x: f(f(x))
>
> (Yes, Python is my favorite Scheme dialect. Why did you ask?)
>
> Note that a number of other languages already allow this. (Racket, 
> Haskell).
>
> You can judge the aesthetics of this on your own code with the 
> following sed command.
>
>   sed 's/\<lambda\>/λ/g'
>
> Advantages:
>
> * The lambda keyword is quite long and distracts from the "meat" of 
> the lambda expression.
>
>   Replacing it by a single-character keyword improves readability.
>
> * The resulting code resembles more closely mathematical notation (in 
> particular, lambda-calculus notation),
>
>   so it brings Python closer to being "executable pseudo-code".
>
> * The alternative spelling λ/lambda is quite intuitive (at least to 
> anybody who knows Greek letters.)
>
> Disadvantages:
>
> For your convenience already noticed here:
>
> * Introducing λ is introducing TIMTOWTDI.
>
> * Hard to type with certain editors.
>
>   But note that the old syntax is still available.
>
>   Easy to fix by upgrading to VIM ;-)
>
> * Will turn a pre-existing legal identifier λ into a keyword.
>
>   So backward-incompatible.
>
> Needless to say, my personal opinion is that the advantages outweigh 
> the disadvantages. ;-)
>
> Greetings,
>
> Stephan
>
>
>
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