Computational Category Theory (404 as of 21 August 2015)
Published in 1990 by D.E. Rydeheard and R.M. Burstall, Computational Category Theory uses ML to illustrate the relevance of category theory to CS.
Updated link: Computational Category Theory by D.E. Rydeheard and R.M. Burstall.
BTW, ML code is available as well.
Enjoy!