http://dev.clojure.org/jira This file is an XML representation of an issue en-us 4.4 649 25-07-2011 http://dev.clojure.org/jira/browse/CLJ-907 Clojure <p>Specify a record with a field as say ^String, but the constructor won't throw if you pass in a non-String.</p> CLJ-907

records do not enforce type hints

Defect Major Closed Declined Unassigned Chip Salzenberg Sun, 8 Jan 2012 01:25:39 -0600 Fri, 1 Mar 2013 12:47:08 -0600 Tue, 27 Nov 2012 13:52:24 -0600 Release 1.2 Release 1.3 1 0 <p>I doubt there's any desire to change this. Records only support typehints to enable performant storage of primitive types like ints, not to provide static typing in general. An Object is stored the same way as a String, so there's no need to pay attention to that typehint.</p> <p>Functions behave the same way: ((fn <span class="error">&#91;^String x&#93;</span> x) :test) works just fine. Only if you use a member method of the hinted type (such as .substring in this example) is an exception thrown then the compiler casts to String in order to call the method.</p> <p>I don't understand how you get from "this is how it is" to "this is how it is meant to be." The compiler can do a better job if the underlying field is properly typed: Type errors can be caught sooner, and cast operations can be omitted on use. This is a worthy enhancement.</p> <p>Alan is correct, the reason type hints exist is to reduce reflection and to allow for the unboxing of primitives. String is not a primitive and therefore type-hinting it only reduces the amount of reflection performed. </p> <p>It has always been Rich's policy that any type systems used in Clojure should not throw compile time errors, but instead should only enhance the performance of existing code. (see the implementation of Typed Clojure for more info on this). </p> <p>Closing this issue, as it is by design. </p> <p>By design. </p> Approval Not Approved Global Rank