Hi
in spite of their similarity, all of these constructs handle some of the monadic aspects differently. the translations of pattern guards not only embed statements in "guard", they also embed the right hand sides of generators in "return". translations of list comprehensions only lift statements. translation of do-notation lifts neither statements nor generators.
does this clarify things?
No. Pattern guards are "obvious", they could only work in one particular way, and they do work that way. They make common things easier, and increase abstraction. If your only argument against them requires category theory, then I'd say that's a pretty solid reason for them going in. The argument that people seem to be making is that they are confusing, I completely disagree. f value | Just match <- lookup value list = g match Without thinking too hard, I am curious how anyone could get the meaning of this wrong if they understand the rest of Haskell. Can you show a concrete example, where you think a user would get confused? Thanks Neil