Will you use lists or arrays?
No, not arrays. I use Haskell from time to time for about three or four years and had succeed not to learn any of array operations at all. That amuses me more than anything else.
Index-less, list-based linear algebra packages have been constructed a few times. There is CLAS of Thorsten Zoerner, in Clean - a language similar to Haskell.
See HBlas of Hal Daume for Haskell. (But you will need CLAPACK; this is a serious, optimized stuff).
Thank you for pointers.
Do you need an elegant toy, or a fast number cruncher?
Elegant and fast enough toy for number crunching. ;) I hope I could use some of techniques from your papers (Generating power of lazy semantics, for example) in this toy, if I succeed. -- Yours truly, Serguey Zefirov, theszATmail.ru.