lisp:land-of-lisp:ch6

lisp/land-of-lisp/ch6/notes.lisp

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+(defun say-hello ()
+	(print "Please type your name:")
+	(let ((name (read)))
+		(print "Nice to meet you, ")
+		(print name)))
+
+;; Type name in quotes in order for it to be a string and not a symbol
+;; When running the function
+
+;; First we print a message asking users for a name
+;; Next we define a local variable called "name" which is set 
+;; to the value returned by (read)
+
+;; (read) will cause lisp to wait for the user to type in something
+;; Only after the user has typed something and pressed ENTER will
+;; the variable name be set to the result
+
+;; Now that we have the user's name, we print a personalized greeting
+
+;; The print command leaves in the quotes when printing to the screen.
+
+;; It is recomended to use (print) or (read) if we can get away with it
+;; in order to save doing extra work. (I still like (format))
+
+;; Basically, (read) and (print) simply take in and spit out things
+;; In a computer understood way. Hence the quotes.
+
+;;Let's do something with numbers
+
+(defun add-five ()
+	(print "please enter a number:")
+	(let ((num (read)))
+		(print "When I add five I get")
+		(print (+ num 5 ))))
+
+;; We can use literal characters by putting #\ in front of it
+;; So we can do #\a to get "a"
+
+;; There are also special characters used this way
+;; #\newline #\tab #\space .. Should be self-explaintory
+
+;; To avoid getting quotes back from print and prin1
+;; we can use (princ)
+
+(progn (princ "This sentence will be interrupted")
+			 (princ #\newline)
+			 (princ "By an annoying newline character."))
+;; >> This sentence will be interrupted
+;; >> by an annoying newline character.
+
+;; This is posibly a better methond than bothering with (format)
+
+;; Now let's create a say-hello function that doesn't suck
+(defun say-hello2 ()
+	(princ "Please type your name:")
+	(let ((name (read-line)))
+		(princ "Nice to meet you, ")
+		(princ name)))
+
+;; This is similar to our original, but now it doesn't 
+;; print quotes around the string.
+;; It just takes everything the user enters as one big string
+
+;; back to the game
+;; So far we've been able to do everything in our game from the lisp repl
+;; this is awesome for prototyping, but it's time to make a real interface
+
+;; (see the new wizard file)