merits of Lisp vs Python

[Kirk Sluder]

In some cases lisp macros are a way of saying tomato to something 
that would be called "tomahto" in python.

One common use of macros is custom iteration constructs. In my 
social network analysis I wanted to do something to each and every 
sender-recipient pair in the header line of "mail" messages in my 
dataset. (And yes, I did have permission to use this data.) Each 
message had one sender, but possibly multiple recipients. Since I 
would be doing multiple forms of analysis, I might as well create 
one iterator to do this.

The DO-MAIL-RELATIONS macro takes the mail message (line), parses 
the sender field and assigns it to (sender), splits the recipient 
field and assigns it to (recip) and then performs the logic in the 
body which often involved looking up values in a database, and 
setting values in a matrix.

(kirk.matrix-process:do-mail-relations (message sender recip)
    ;;about 12 lines of logic snipped
    )

To be pedantic about this call. "KIRK.MATRIX-PROCESS" identifies the 
package/namespace for the macro call. "DO-MAIL-RELATIONS" names the 
macro as part of the DO family of iteration constructs which are 
basic to lisp.

Now that I think about this, in python I'd probably do this using 
object logic that returned the recipient list as an iteratable 
object:

for sender, recipient in message.relationPairs:
   #about 12 lines of logic

Would it have been possible to implement DO-MAIL-RELATIONS as a 
function? Possibly, but I found trying to compact all of that logic 
into a single-use function that could be safely passed to another 
function to be more trouble.

Another common macro use is the "WITH-STREAM" family which opens a 
stream for IO and closes it at the end.  
(with-open-file (file-handle "filename" :direction :output)
   (format file-handle "Hello world.~%")
) 

The pythonic way to do this would be to create a class that 
implements file-like behaviors:

output = fileLike.open()
output.write("Hello world\n")
output.close()

You might want to use a custom "WITH-STREAM" macro or file-like 
object if you need to format, filter, or compress the outgoing 
stream in any way.