common-lisp

问题 In Clojure you can update a map (dict) with assoc-in and create key path automatically if it don't exist. (assoc-in {:a 1 :b 3} [:c :d] 33) ; {:a 1, :c {:d 33}, :b 3} Same for get-in: you can specify a path of keys (or list indices) and it will return the value specified by the path, nil if it does not exist. (get-in {:a 1, :c {:d 33}, :b 3} [:c :d]) ; 33 (get-in {:a 1, :c {:d 33}, :b 3} [:c :e]) ; nil I like to have the sugar in Common lisp,so I monkeyed a 'assoc-in' and I tested it on a

问题 I've found some techniques in other SO answers, but apparently I've been unable to convince SBCL to do inline fixnum arithmetic: (declaim (optimize (speed 2) (safety 1))) (declaim (ftype (function (fixnum fixnum) double-float) fixnumtest) (inline fixnumtest)) (defun fixnumtest (i j) (declare (type fixnum i j)) (let* ((n (the fixnum (+ i j))) (n+1 (the fixnum (1+ n)))) (declare (type fixnum n n+1)) (/ 1.0d0 (the fixnum (* n n+1)) ) ) ) (defun main () (format t "~11,9F~%" (fixnumtest 2 3)) )

问题 I've found some techniques in other SO answers, but apparently I've been unable to convince SBCL to do inline fixnum arithmetic: (declaim (optimize (speed 2) (safety 1))) (declaim (ftype (function (fixnum fixnum) double-float) fixnumtest) (inline fixnumtest)) (defun fixnumtest (i j) (declare (type fixnum i j)) (let* ((n (the fixnum (+ i j))) (n+1 (the fixnum (1+ n)))) (declare (type fixnum n n+1)) (/ 1.0d0 (the fixnum (* n n+1)) ) ) ) (defun main () (format t "~11,9F~%" (fixnumtest 2 3)) )

问题 We find this function builder to realize composition in P.Graham's "ANSI Common Lisp" (page 110). The arguments are n>0 quoted function names. I don't understand it completely, so I'll quote the code here and specify my questions underneath it: (defun compose (&rest fns) (destructuring-bind (fn1 . rest) (reverse fns) #'(lambda (&rest args) (reduce #'(lambda (v f) (funcall f v)) rest :initial-value (apply fn1 args))))) The argument list to compose is reversed and unpacked, its (now first)

问题 We find this function builder to realize composition in P.Graham's "ANSI Common Lisp" (page 110). The arguments are n>0 quoted function names. I don't understand it completely, so I'll quote the code here and specify my questions underneath it: (defun compose (&rest fns) (destructuring-bind (fn1 . rest) (reverse fns) #'(lambda (&rest args) (reduce #'(lambda (v f) (funcall f v)) rest :initial-value (apply fn1 args))))) The argument list to compose is reversed and unpacked, its (now first)

问题 I'm busy learning Common Lisp, & I'm looking for a static code analysis tool that will help me develop better style & avoid falling into common traps. I've found Lisp Critic and I think it looks good, but I was hoping that someone may be able to recommend some other tools, and / or share their experiences with them. 回答1: Given the dynamic nature of Lisp, static analysis is everything from tough to impossible, depending on the type of source code. For some purposes I would recommend using the

问题 It is a technique used frequently in On Lisp , which is on Common Lisp: > (mapcar #'(lambda (x) (+ x 10)) '(1 2 3)) (11 12 13) Why is sharp-quote needed or even possible? lambda expressions return function objects, and sharp quoting returns function objects from names. I also have heard contradictory information on whether lambda expressions are names - in particular On Lisp contradicts the standard, but his code seems to work which also contradicts the standard. In elisp it seems it's not

问题 It is a technique used frequently in On Lisp , which is on Common Lisp: > (mapcar #'(lambda (x) (+ x 10)) '(1 2 3)) (11 12 13) Why is sharp-quote needed or even possible? lambda expressions return function objects, and sharp quoting returns function objects from names. I also have heard contradictory information on whether lambda expressions are names - in particular On Lisp contradicts the standard, but his code seems to work which also contradicts the standard. In elisp it seems it's not

问题 If I write a file using (with-open-file (s "~/example.sexp" :direction :output) (write '(1 2 3) :stream s) (write '(4 5 6) :stream s) (write '(7 8 9) :stream s)) A file is created containing (1 2 3)(4 5 6)(7 8 9) But when I attempt to open and read it using (setf f (open "~/example.sexp")) (read :input-stream f) I get an ":INPUT-STREAM is not of type STREAM" error. (type-of f) returns STREAM::LATIN-1-FILE-STREAM which looks like it is at least close to what I need. What is the difference? How

问题 If I write a file using (with-open-file (s "~/example.sexp" :direction :output) (write '(1 2 3) :stream s) (write '(4 5 6) :stream s) (write '(7 8 9) :stream s)) A file is created containing (1 2 3)(4 5 6)(7 8 9) But when I attempt to open and read it using (setf f (open "~/example.sexp")) (read :input-stream f) I get an ":INPUT-STREAM is not of type STREAM" error. (type-of f) returns STREAM::LATIN-1-FILE-STREAM which looks like it is at least close to what I need. What is the difference? How