[Haskell-cafe] [Agda] Defining subtraction for naturals

Nils Anders Danielsson nad at chalmers.se
Thu Mar 17 21:00:22 CET 2011

On 2011-03-17 19:35, wren ng thornton wrote:
> Dependently typed languages tend to use the second definition because it
> gives a pure total function (unlike the first) and because it's less
> obnoxious to use than the third. In Haskell the third would be even more
> obnoxious.

There is a fourth option: a comparison view. See "The view from the
left" by Conor McBride and James McKinna (Section 6).

(This option is similar to what Henning Thielemann suggested.)


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