Why is Python popular, while Lisp and Scheme aren't?

[Fernando Pereira]

On 12/1/02 7:25 PM, in article
PMxG9.49830$HU.3568244 at news010.worldonline.dk, "Anders J. Munch"
<andersjm at inbound.dk> wrote:
> But I don't like the verbosity and reliance on positional information,
> that comes with the s-expression syntax that implements code-as-data.
> So it's a tradeoff.  Syntax is my primary interface with my programs,
> so I prioritize that highly.  Your tradeoff, it seems, is different.

This is an interesting point. This discussion is really about the cognitive
load of Lisp syntax processing *for people*. Psycholinguists have shown
conclusively that deeply embedded constructions are hard to process.
Basically, we are not very good at counting on the fly. Other cognitive
science evidence shows that we can recognize groups of up to three things at
a glance, but groups with more elements require deliberate sequential
processing. Various notational devices such as infix notation and operator
precedence reduce processing load by favoring left- or right-recursive
expressions. Python goes even further by getting rid of most brackets in
favor of required and visually evident indentation.

Much that I like Lisp (er, Scheme), this cognitive issue is non-trivial. If
Lisp had been well promoted at the right time, enough people would have
become dependent of its great power that the cognitive cost would have been
worth paying, but as it is, for many tasks and for much of the time there
are cognitively less burdensome languages to choose amongst.

However, ignoring Lisp may be costly too. The most powerful tools are often
hard to learn. How do you know what you are missing?

-- F