February 2016 Archives

Apropos proto: Perl6.c multi thoughts

Multi routines are pretty neat, but seem incomplete to me. Some background- one can compute factorials this way:

multi fac(0) { 1 }
multi fac(Int $n where 1..Inf) { $n * fac( $n-1 ) }
say fac(4); # 24

Now what if we want to pass our recursive-multi-sub "fac" as a callback?

given &fac -> $some_fun { say "some_fun(4)=",$some_fun(4) }

Now... what about defining an anonymous multi-sub?

Text, Grammar, Tree- the 3

I think of text, grammars that parse the text, and the syntax trees (data) generated by a parser as a triangle. Most of the time in computerland, people doing something with this triangle are interested in converting a text into a tree using a parser.

Every once in a while I need to write a parser. My first serious parser was in the late 90's, for a radio station that needed each week to convert a large plain-text weekly email to tables of venues and shows. For that, I used a version of Bison (yacc) that allowed me to write actions in Perl./users/yary/2016/02/index.html

About Yary

user-pic Programming for decades, and learning something new every day.