> you can multiply n by k, k by m matrices to get an n by m matrix, but anything... | Hacker News

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		freyrs3 on June 15, 2014 \| parent \| context \| favorite \| on: Reasons to use Haskell as a Mathematician (2006) > you can multiply n by k, k by m matrices to get an n by m matrix, but anything else is a type error. This is exactly how Repa works, it uses a Peano encoding of the extent of dimensions to make invalid array operations inexpressible.

seanmcdirmid on June 15, 2014 [–]

Ok. This isn't obvious at all by looking at the documentation, also since extent doesn't seem to appear in the type signature of a matrix instance.

on June 15, 2014 | [2 more]

[deleted]

seanmcdirmid on June 15, 2014 | | [–]

Ah, this is exactly the approach I took in C# (though with a small range of branded types to stand in for numbers). Thanks for clearing this up!

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