#’foo is an abbreviation for (function foo) by the reader. In CL, there are several different namespaces, #’foo or (function foo) will return the functional value of foo. You may want to search for “Lisp-1 vs. Lisp-2”, check other Stackoverflow questions, or read an old article by Pitman and Gabriel in order to learn more … Read more
Try reading Practical Common Lisp, by Peter Seibel.
Two possible solutions: I. You can use the format directives ~:A or ~:S (format t “~:a” ‘()) => () However, this directive works only on the top level elements of a list, i.e. (format t “~:a” ‘(a b () c)) will not print (A B () C) but (A B NIL C) So you need … Read more
What’s going on? You say: feel like there is nothing special is going on here. The outer foo in bar increments the global x, and foo surrounded by let in bar increments the shadowed x. What’s the big deal? The special that’s going on here is that LET can shadow the value of *x*. With … Read more
Basic Predicates/F-functions McCarthy‘s Elementary S-functions and Predicates were: atom Which was necessary because car and cdr are defined for lists only, which means you cannot count on any sort of answer to indicate what was happening if you gave car an atom. eq For testing equality between atoms. car For returning the first half (address) … Read more
It’s nice to see so many solutions: ~A, ~<, and ~{ so far. The ~@{ iteration construct provides a concise solution: (format nil “~v@{~A~:*~}” 3 #\*)
Here’s what I’d do: (ql:quickload “alexandria”) (alexandria:flatten list) That works mainly because I have Quicklisp installed already.
Use FORMAT. ~{ and ~} denote iteration, ~A denotes aesthetic printing, and ~^ (aka Tilde Circumflex in the docs) denotes printing the , only when something follows it. * (format nil “~{~A~^, ~}” ‘( 1 2 3 4 )) “1, 2, 3, 4” *
LET itself is not a real primitive in a Functional Programming Language, since it can replaced with LAMBDA. Like this: (let ((a1 b1) (a2 b2) … (an bn)) (some-code a1 a2 … an)) is similar to ((lambda (a1 a2 … an) (some-code a1 a2 … an)) b1 b2 … bn) But (let* ((a1 b1) (a2 … Read more
Originally, in Lisp, there were no lexical variables — only dynamic ones. And there was no SETQ or SETF, just the SET function. What is now written as: (setf (symbol-value ‘*foo*) 42) was written as: (set (quote *foo*) 42) which was eventually abbreviavated to SETQ (SET Quoted): (setq *foo* 42) Then lexical variables happened, and … Read more