Ave1

Why do you want strings ? What do you use them for ? Why are you using strings for that ? And so following.

Mircea Popescu

For years, I have wanted to break free of the tools of the Inca; Python, Matlab, Octave. These go-to languages to quickly and easily make something sort of work. I'm now working in a position where another set of tools is used, Word, Outlook, Excel. These are a step worse. Each time, I trade short term gains for long term costs. And those costs are mounting. This cannot stand. So, I want to work towards some sort of solid ground (learn Ada, pin down gnat,  read ffa). And also, use Common Lisp for those cases where I would normally go for Python and friends.

Next part of the why, I want to make diagrams like so. I've found no tools to help me with this on the long term;

1. GUI Based diagram editors; Every editor comes with handy ways to make boxes with text,  support to put links between these boxes  and to make a sort of layout. But, for every change you will have to work on the entire diagram. Plus I do not want to become a proficient mouse worker.
2. Graphviz; It sort of works, diagrams can be entered but to layout a diagram you I'll need to perform a feedback loop (change a parameter (like the order of the links), make graph, look at result, change another parameter, ...). The problem is that this loop is needed for every change, or simply give up on layout and then why are you doing it?.

(defun strcat (a b) (concatenate 'string a b))
(defun spacedstrcat (a b) (concatenate 'string a " " b))

(defun strlistcat (list)(reduce (lambda (a b) (concatenate 'string a b)) alist))

(defun xmlresttag (tag content)
  (if (and content (> (length content) 0))
      (strcat content (strcat (strcat "</" tag) ">"))
      "/>"))

(defun xmlbegintag (tag) (strcat "<" tag))
(defun xmlattribute (attribute) )
(defun xmlattibutes (attributes &key id class)
  (strlistcat (map xmlattribute attributes))

(defun xmlelement (tag content attributes &key id class)
  (spacedstrcat(spacedstrcat (begintag tag) (xmlattributes attributes :id id :class class))
               (xmlresttag (tag content))))

(defun rectangle (x y width height &key (content "") id class)
  ())

(defun assert-equals (a b)
  (if (string= a b) ()
      (progn (pprint `("not equals" ,a ,b) )
             (cerror "assertion failed" "abort"))))

(defun test$strcat ()
  (assert-equals (strcat "a" "b") "ab")
  (assert-equals (strcat "this" " is a test") "this is a test"))

(defun test$spacedstrcat ()
  (assert-equals (spacedstrcat "a" "b") "a b")
  (assert-equals (spacedstrcat "this" "is a test") "this is a test"))

(defun test$xmlresttag ()
  (assert-equals (xmlresttag "first" "") "/>")
  (assert-equals (xmlresttag "second" NIL) "/>")
  (assert-equals (xmlresttag "hello" "world") "world</hello>"))

(defun test$xmlbegintag ()
  (assert-equals (xmlbegintag "first") "<first"))

(defun run-tests ()
  (test$strcat)
  (test$spacedstrcat)
  (test$xmlresttag)
  (test$xmlbegintag))

The whole artifact is resting on the weak shoulders of concatenate and the wrong concept of  merging pieces of text into bigger pieces of text. I am thinking that constructing lists of strings will be a big improvement and then have a function whereby the whole list is output as svg text.

1. I'm  avoiding the terms string and sentence [↩]

This entry was posted on Thursday, August 1st, 2019 at 12:35 and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.