This has nothing to do with Ruby -- I thought there might just be some Io users here, and I didn't want to sign up for some Io mailing list just for this one question. I'm trying to implement Enumerable#inject in Io, just because I'd like to get a sense of the language. I've tried this: List inject := method(n, blk, self foreach(v, n = blk call(n, v))) but when running this: list(1, 2, 3) inject(0, block(n, v, n + v)) I get this error: Importer: Nil does not respond to '+' What am I doing wrong? Daniel