paste into the interp; string coercion

[Ka-Ping Yee]

> >Was there any intention of being able to copy and paste
> >multi-line blocks of interactive sessions?  It sure would be
> >neat if E knew enough to strip the leading prompt from each
> >line.  (It is fairly annoying to have to cut and paste each
> >line individually in Python when i make a mistake, and of
> >course this is exacerbated by Python's indent sensitivity
> >which doesn't occur here.)
> 
> Thank you, I now have my first satisfying answer for why I avoid
> indentation-significance.

Gee, i was kind of surprised to hear you say this.  If i had
known that you didn't have a satisfying answer the Python-lover
in me might even have asked for indentation...

But i really thought the original strongest argument had to do
with entering arbitrary code on the command line.  If you use
indentation for block structure and/or scoping, then there is
only a limited amount you can say on one line.

Do you think it's a good idea to make the E interpreter remove
leading "?"s and ">"s from lines of input?



> On int("4"), introspectively, I only find a surprisingly inarticulate
> "that's not coercion, that's parsing!".  I may just be confused, I'll stew
> further.

Hmm.  Well, it is a simple kind of parsing.  But how else
are you going to get an int out of a string, except by
parsing?  The strongest argument for me in favour of int("4")
producing 4 is that string(4) yields "4".  (Similarly i think
many people would expect that float(string(3.14)) or
double(string(3.14)) produced 3.14 too.)

Guido resisted this in Python for a while (i believe with a
similar "but that's parsing" reply), but finally the
clamouring grew too loud and he relented in Python 1.5, in which
the built-in functions int() and float() now accept a string.

> On 
> 
> 	'a' -> "a"
> 
> how would you feel about 
> 
> 	3 -> [3]
> ?

Actually, i think i would be okay with it -- if you first
properly extend the analogy:

    char is the character type
    string is a "sequence of characters" type

    int is the integer type
    intlist is a "sequence of integers" type

Now, does

    intlist(3) -> [3]

seem more reasonable?

I guess my point is, sequence-ness is embedded in the
meaning of "string".  So it's okay to get "a" from string('a').

That's a justification from a semantic standpoint.  The style
justification is that "string('a')" looks like other coercers.

In any case, i imagine that string('c') probably won't be
used extremely often anyway, since most of the time you'll
probably be tacking characters onto strings with + or
something like that.


!ping