Media type: E-Article Title: Type-extension type test can be performed in constant time Contributor: Cohen, Norman H. imprint: Association for Computing Machinery (ACM), 1991 Published in: ACM Transactions on Programming Languages and Systems Language: English DOI: 10.1145/115372.115297 ISSN: 0164-0925; 1558-4593 Keywords: Software Origination: Footnote: