Hello,<div><br></div><div>I&#39;m a beginner in Haskell, so forgive me if this is a basic question, but I&#39;d like to know if it&#39;s possible to have a predicate as part of a data type, so that when the data type is created, it can only be done if it satisfies the predicate else a type error is thrown.</div>

<div><br></div><div>For instance, a matrix with integer elements could be modelled as [[Int]], given the restrictions that </div><div><ul><li>it must have at least one column and one row (so there must be at least one list), and</li>
<li>every list must have the same length</li></ul><div>so that when a matrix is created, the type system wont allow it if the predicates aren&#39;t met.</div></div><div><br></div><div>Thanks,</div><div><br></div><div>Navid</div>