On Fri, May 10, 2013 at 8:30 AM, Ian Kelly <ian.g.ke...@gmail.com> wrote: > On Thu, May 9, 2013 at 3:51 PM, Mark Janssen <dreamingforw...@gmail.com> > wrote: >> the community stays fractured. > > The open source community seems pretty healthy to me. What is the > basis of your claim that it is "fractured"?
The carpentry community is fractured. There are people who use screwdrivers, and there are people who use hammers! Screws and nails are such completely different things that we shouldn't try to use the same language to discuss them. >> Language "expressivity" can be measured. > > And the measurements can be endlessly debated. Expressivity is not > the sole measure of a programming language, though. Every programming language can encode every program. It's fairly straightforward to prove that a Python interpreter can be written in Ruby, or a C interpreter in Lua; so there is no program that can be expressed in one language and not in another (there will be apparent exceptions, eg web-browser JavaScript cannot call on arbitrary C-level functionality, but if the entirety of program code were written in C, then it could all be interpreted by one C interpreter). Larry Wall of Perl put it this way, in a State of the Onion address: http://www.perl.com/pub/2007/12/06/soto-11.html """... Human languages are Turing complete, as it were. Human languages therefore differ not so much in what you can say but in what you must say. In English, you are forced to differentiate singular from plural. In Japanese, you don't have to distinguish singular from plural, but you do have to pick a specific level of politeness, taking into account not only your degree of respect for the person you're talking to, but also your degree of respect for the person or thing you're talking about. So languages differ in what you're forced to say. Obviously, if your language forces you to say something, you can't be concise in that particular dimension using your language. Which brings us back to scripting. How many ways are there for different scripting languages to be concise? """ In C, for example, you are forced to write explicit notation representing {blocks; of; code;} and explicit characters separating; statements;. In Python, on the other hand, you have to write out your indentation. In Java, you state what exceptions you might throw. REXX mandates that you annotate procedures with their list of exposed names (effectively, non-local and global variables). So the expressivity of a language can't be defined in terms of how many programs can be written in it, but in how concisely they can be written - and that's something that depends on specific design choices and how they align with the code you're trying to write. Compare these two snippets: #!/bin/sh pg_dumpall | gzip | ssh user@host 'gzip -d|psql' #!/usr/bin/env python words=input("Enter words, blank delimited: ") lengths=[len(x) for x in words.split(" ")] print("Average word length: %d"%int(sum(lengths)/len(lengths))) Could you write each in the other's language? Sure! But it won't be as concise. (The Python version of the shell script could cheat and just call on the shell to do the work, but even that would add the expressive overhead of "os.system".) This is why there are so many languages: because each is good at something different. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
