Return-Path: <samepst@cs.bu.edu> X-Spam-HitLevel: X-Spam-DCC: CTc-dcc2: cs3.bu.edu 1031; Body=1 Fuz1=1 Fuz2=1 X-Spam-Checker-Version: SpamAssassin 3.1.0 (2005-09-13) on cs3.bu.edu X-Spam-Level: X-Spam-Status: No, score=-3.4 required=10.0 tests=ALL_TRUSTED,BAYES_00, NO_REAL_NAME autolearn=ham version=3.1.0 X-Spam-Pyzor: Received: from csa3.bu.edu (csa3 [128.197.12.5]) by cs3.bu.edu (8.13.6/8.13.6) with ESMTP id kAK2lYl8018212 for <cs520@cs.bu.edu>; Sun, 19 Nov 2006 21:47:34 -0500 Received: (from apache@localhost) by csa3.bu.edu (8.13.6/8.12.11/Submit) id kAK2lYCo017170; Sun, 19 Nov 2006 21:47:34 -0500 X-Authentication-Warning: csa3.bu.edu: apache set sender to samepst@cs.bu.edu using -f Received: from 71.192.166.44 (SquirrelMail authenticated user samepst) by cs-squirrelmail.bu.edu with HTTP; Sun, 19 Nov 2006 21:47:34 -0500 (EST) Message-ID: <1667.71.192.166.44.1163990854.squirrel@cs-squirrelmail.bu.edu> Date: Sun, 19 Nov 2006 21:47:34 -0500 (EST) Subject: Programming Assignment 4 From: samepst@cs.bu.edu To: cs520@cs.bu.edu User-Agent: SquirrelMail/1.4.6-4.fc2.1.legacy Content-Type: text/plain;charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Priority: 3 (Normal) Importance: Normal X-Clamav-Status: No Status: RO Content-Length: 420 X-UID: 53 X-Keywords:
During the implementation of pa4, I ran into a problem with the rule
CT-proj. Here is an example of a term t which produces the error:
t= (lam (x: int) => (5,x)) 4
t is typed by CT-App:
t:X |(int->(int*int) = int->X
However CT-Proj cannot be applied to
t.2
because t is of type X instead of T1*T2*..Tn
Type X cannot be determined until unification, so my typechecker fails at
this point.
Thank you,
-Sam Epstein
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