The program definition:
The program listens to 'http://localhost:8080/said'. First it shows a
page with an input field and a submit button. Clicking the submit
button shows another page with a link saying "click here". Clicking
the link shows the last page with the text "You said: " along with the
text typed in on the first page.
One might say that this is the definition, but in fact this is the
solution. The verbs 'listen', 'show', 'click' and the nouns 'input
field', 'submit button', 'link' or the reference 'the text typed in on
the first page' are all context sensitive. A human can interpret this
program by using some paper and a pen while another human could be a
user. Unfortunately a computer cannot yet do this.
So how do you write it in lisp? Well, the best advice here is if you
still have a couple then use your father's parenthesis. Otherwise you
will have to make up some new ones such as.
(entry "http://localhost:8080/said"
(show
(input-field a)
(submit-button
(show
(link "Click here"
(show (text "You said: " a)))))))
Defining the terms entry, show, input-field, submit-button, link and
text in a 'framework' of your choice is left to the reader as an
exercise. Each one of those are generic concepts.
levy