<p><a href="http://www.iai.uni-bonn.de/~jv/free-slides.pdf">http://www.iai.uni-bonn.de/~jv/free-slides.pdf</a></p>

<p><a href="http://daniel.yokomizo.org/2011/12/understanding-higher-order-code-for.html">http://daniel.yokomizo.org/2011/12/understanding-higher-order-code-for.html</a></p>

<p><a href="http://arxiv.org/pdf/1107.1203.pdf">http://arxiv.org/pdf/1107.1203.pdf</a></p>

<p>(Also in typeclassopedia Section 3.3)</p>

<p><a href="http://hackage.haskell.org/package/free-theorems-seq">http://hackage.haskell.org/package/free-theorems-seq</a></p>

<p><a href="http://hackage.haskell.org/package/free-theorems-counterexamples">http://hackage.haskell.org/package/free-theorems-counterexamples</a></p>
Good introduction to free theorems
<p>I stumbled upon a nice idea of <a href="http://www-ps.iai.uni-bonn.de/cgi-bin/free-theorems-webui.cgi?help" rel="noreferrer">free theorems</a> in functional language. However, the only resource I was able to find is Wadler's article "<a href="http://doi.acm.org/10.1145/99370.99404" rel="noreferrer">Theorems for Free</a>". It's quite good but it definitely not a tutorial and hard for me to get through (I understood about half of it and it required for me to spend quite a lot of time). Can you recommend me another article or tutorial which is oriented towards a software developer familiar with functional programming instead of hard core functional language researcher?</p>

<p>Thanks.</p>