[Haskell-cafe] New type of ($) operator in GHC 8.0 is problematic

butrfeld Andrew.Butterfield at scss.tcd.ie
Tue Feb 9 18:11:24 UTC 2016

> On 9 Feb 2016, at 17:17, Joachim Durchholz <jo at durchholz.org> wrote:
> I feel that this is similar to expressing value constraints in the type system, e.g. ranges or squareness of matrixes. Yes it can be done in Haskell's type system, yes it does typecheck beautifully, but the type declarations behind these kinds of feats will just make any ordinary programmer go MEGO. Even the bright ones.
> I conclude that the type system isn't the right place for that kind of checking. To be understandable, such constraints need to be expressed as boolean assertions, not as some inductive construct. YMMV.

+n to that, as n -> \infty

Andrew Butterfield
School of Computer Science & Statistics
Trinity College
Dublin 2, Ireland

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