Option to run the program on each line of stdin

[dloscutoff]

Inspired by Perl's -n and -p flags, supposing we had one or two flags that ran an implicit loop over all lines of stdin and called the given code as a function on each line? I'm thinking something like this:

T (a:q) == ()
 P {

  ; Your code here

 } V (g PE a)

corresponding to perl -p and the same thing without the P for perl -n.

• It loops over all lines of stdin and runs your code against each one.
• The final expression in your code is autoprinted. You can specify whatever list format you like via command-line argument.
• Inside your code, the line of stdin is a; the actual command-line arguments are still accessible as b through e and also @>g.
• Global variables retain their values from one iteration to the next (unless you don't want them to, in which case you can lead with WG).
• Your code can call itself recursively using f.

One question: what actual flags do we use, since -n and -p (and -P) are already taken--as are -e (for Each) and -l (for Line)?

[dloscutoff]

Given the philosophy change in #42, flags should not be used for this purpose. But I think we could still implement the behavior using a character added to the beginning or end of the program.