On 10/30/2017 12:23 AM, Rustom Mody wrote:
On Sunday, October 29, 2017 at 9:52:01 PM UTC+5:30, Rick Johnson wrote:
On Sunday, October 29, 2017 at 9:19:03 AM UTC-5, Alberto Riva wrote:
In a language like Lisp
Python is nothing like Lisp, and for good reason! Sure, we
have a few lispers and functional fanboys who hang around
here, and sometimes Rustom can get a little preachy about
FP, but mostly, we tolerate the fanboyism -- so long as it's
not rabid fanboyism.
Rick's personal comments are one of the standard entertainments of this list.
Enjoy!
The comments on FP are more problematic:
- These misconceptions are more widespread than just Rick
- They are right enough to be hard to refute
- And wrong enough to cause confusion and misdirection
- And irrelevant to (threads like) this one
My super-short rejoiner to the FP-irrelevancy is:
«If there is one key takeaway from functional programming maybe it should be: "Truth
is a function of time" »
In more detail:
- Lisp (1960) was the second functional language; its predecessor was
something called Formula Translator — usually shortened to Fortran (c. 1957)
- By the late 80s, many FPers had begun regard Lisp as a setback for functional
programming. [Dont get me wrong: Ive enjoyed Scheme more than any other
programming language. Its just that conflating Lisp and FP is an error (in
2017)]
More historical details at http://blog.languager.org/2015/04/cs-history-1.html
and sequel
At a more conceptual level, people dont get that there are two dimensions
- the apply-lambda axis — usually called functional programming
- the eval-quote axis — which has precious little to do with FP (and is more
relevant to your question)
These two dimensions of power uniquely coincide in Lisp (Scheme).
As you correctly (almost) point out
- Python is very much a lisp… its semantic under-belly
- However, syntactically its more like C/Java etc in the sense of having a rigid
fixed-at-language-design-time syntax
More at http://blog.languager.org/2013/08/applying-si-on-sicp.html
For a question like macros (syntax-extensions) that sits between the two your
question is interesting and I am not sure I know how to do it…
I remember seeing something about this recently but my google-foo is failing me
at the moment
However I would look at
- PEP 263 https://www.python.org/dev/peps/pep-0263/ — Source Code Encodings…
- Hooking into the codec module https://docs.python.org/3/library/codecs.html
- hooking into ast module https://docs.python.org/3/library/ast.html
An old attempt in this direction: http://code.activestate.com/recipes/546539/
You've already got the moral-hi-horse guys giving you the dope of why this is
evil. Swallow if you like. My own lightweight
suggestion would be that the natural pythonic way of unstructured exit is
exceptions. Not as succinct as a tailormade syntax extension. But good enough
IMHO
PS I personally would be interested if you get this (syntax extension) running
Thanks for the interesting reply! But once again: I was not proposing to
add lisp-style macros to Python; I have no interest in doing that since
I believe it's pretty much impossible :)
Thanks!
Alberto
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