I was playing around with another ITA hiring puzzle today and needed to “slice” a sequence of words. That is, I wanted to form a list of strings consisting of the first letters of each word, the second letters of each word and so on. For example
hand lest more → hlm aeo nsr dte
Think of writing the words down in rows
hand lest more
and forming the slices by reading down each column.
This turns out to be simpler to do in Elisp than in Common Lisp (although it’s not really hard in CL). The thing that makes it easy is the string function, which takes a sequence of characters and turns them into a string:
ELISP> (string ?a ?b ?c)
"abc"
Common Lisp also has a string function but it behaves differently. Here’s how to slice words in Elisp
ELISP> (map 'list #'string "hand" "lest" "more") ("hlm" "aeo" "nsr" "dte")
This is nothing earth-shattering, of course, but it does serve as a nice example of the conciseness of Lisp in general and of Elisp in particular.