Mercurial > urweb
comparison demo/prose @ 406:a71600cac815
Form example
| author | Adam Chlipala <adamc@hcoop.net> |
|---|---|
| date | Tue, 21 Oct 2008 17:30:06 -0400 |
| parents | 948315ea84c3 |
| children | 345fcf91c806 |
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| 405:948315ea84c3 | 406:a71600cac815 |
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| 34 | 34 |
| 35 <p>Looking at <tt>hello.ur</tt>, we see an SML-looking function definition that returns a fragment of XML, written with special syntax. This fragment is returned to browsers that request the URI <tt>/Demo/Hello/main</tt>. That is, we take the demo-wide prefix <tt>/Demo</tt> and add a suffix that indicates we want to call the <tt>main</tt> function in the <tt>Hello</tt> module. This path convention generalizes to arbitrary levels of nested module definitions and functor applications (which we will see later).</p> | 35 <p>Looking at <tt>hello.ur</tt>, we see an SML-looking function definition that returns a fragment of XML, written with special syntax. This fragment is returned to browsers that request the URI <tt>/Demo/Hello/main</tt>. That is, we take the demo-wide prefix <tt>/Demo</tt> and add a suffix that indicates we want to call the <tt>main</tt> function in the <tt>Hello</tt> module. This path convention generalizes to arbitrary levels of nested module definitions and functor applications (which we will see later).</p> |
| 36 | 36 |
| 37 link.urp | 37 link.urp |
| 38 | 38 |
| 39 <p>This is my second favorite.</p> | 39 <p>In <tt>link.ur</tt>, we see how easy it is to link to another page. The Ur/Web compiler guarantees that all links are valid. We just write some Ur/Web code inside an "antiquote" in our XML, denoting a transaction that will produce the new page if the link is clicked.</p> |
| 40 | |
| 41 form.urp | |
| 42 | |
| 43 <p>Here we see a basic form. The type system tracks which form inputs we include, and it enforces that the form handler function expects a record containing exactly those fields, with exactly the proper types.</p> | |
| 44 | |
| 45 <p>In the implementation of <tt>handler</tt>, we see the notation <tt>{[...]}</tt>, which uses type classes to inject values of different types (<tt>string</tt> and <tt>bool</tt> in this case) into XML. It's probably worth stating explicitly that XML fragments <i>are not strings</i>, so that the type-checker will enforce that our final piece of XML is valid.</p> | |
| 40 | 46 |
| 41 listShop.urp | 47 listShop.urp |
| 42 | 48 |
| 43 <p>This is my other favorite.</p> | 49 <p>This is my other favorite.</p> |