[Haskell-cafe] Very Small Program

Hello, I just found it (in ghci and hugs) that this is a valid haskell program: let 0 = 1 in 0 This program evaluates to 0 (to my surprise). I expected something similar to how this works: let { 1 + 1 = 3; 3 + 1 = 7 } in 1 + 1 + 1 Where you get 7. So, if the 0 is not used as an identifier (ie, defining a function or name of a value), then why doesn't this count as a parse error? And, why didn't I get to locally redefine it? Thanks, Jason