What steps will reproduce the problem? 1. try to execute var Triple = D("Triple = T Int Int Int"); var triple = Triple.T(1, 2, 3)

Expected: an object triple with triple[0] = 1, triple[1] = 2, triple[2] = 3 Result: a TypeError

Note that this also happens with: var genTriple = T( "Int -> Int -> Int -> [Int]", function() { return [].slice.apply(arguments); } );

The problem appears to be associated with numArgs in FunctionContract.restrict being set to 0, then becoming negative during recursion. When there are only two arguments, then the first argument has an argCount of 0, and the second invokes an alternative code path as there's no further FunctionContract to recurse to. On the other hand, if there are more than two arguments then the first recursive step has an argCount of -1 and this causes an error.