Multiple Values in CL The language Common lisp is described in the ANSI standard INCITS 226-1994 (R2004) and has many implementations. Each can implement multiple values as it sees fit, and they are allowed, of course, to cons up a list for them (in fact, the Emacs Lisp compatibility layer for CL does just that … Read more
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” *
The two different approaches have names: Lisp-1 and Lisp-2. A Lisp-1 has a single namespace for both variables and functions (as in Scheme) while a Lisp-2 has separate namespaces for variables and functions (as in Common Lisp). I mention this because you may not be aware of the terminology since you didn’t refer to it … Read more
Strictly speaking, funcall would not be needed, but there are some lisps (lisp-2 variants, such as Common Lisp) that separate the variable name space of the function name space. Lisp-1 variants (e.g. Scheme) do not make this distinction. More specifically, in your case, test-func is in the variable name space. (defun foo (test-func args) (funcall … Read more
Start with Emacs Lisp (given that you seem to have already started customizing your emacs) – it seems to be more immediately useful for you. Do keep in mind that there is quite a bit of difference between Emacs Lisp (there is a lot of buffer management stuff, especially in the code you’re likely to … Read more
Dynamic dispatch and namespace resolution are two different things. In many object systems classes are also used for namespaces. Also note that often both the class and the namespace are tied to a file. So these object systems conflate at least three things: class definitions with their slots and methods the namespace for identifiers the … Read more
The actual meaning of F is often forgotten. According to some sources, f suffix could stand for: Field (see for example this answer) Form (as seen in various teaching materials and manuals) However, according to Gabriel and Steele’s The Evolution of Lisp, SETF comes from Peter Deutsch’s A Lisp Machine with Very Compact Programs (published … Read more
Use the built-in “+” or “-” functions, or their shorthand “1+” or “1-“, if you just want to use the result, without modifying the original number (the argument). If you do want to modify the original place (containing a number), then use the built-in “incf” or “decf” functions. Using the addition operator: (setf num 41) … Read more
setq assigns a value to a variable, whereas let introduces new variables/bindings. E.g., look what happens in (let ((x 3)) (print x) ; a (let ((x 89)) (print x) ; b (setq x 73) (print x)) ; c (print x)) ; d 3 ; a 89 ; b 73 ; c 3 ; d The … Read more
In Common Lisp, ‘1 is shorthand for (QUOTE 1). When evaluated, (QUOTE something) returns the something part, unevaluated. However, there is no difference between 1 evaluated and 1 unevaluated. So there is a difference to the reader: ‘1 reads as (QUOTE 1) and 1 reads as 1. But there is no difference when evaluted.