Especially after writing a partial lexer for Haskell, I opine that this should be all legal: module Foo where --in case you didn't know, this is legal syntax: Foo.f = undefined Foo.mdo = undefined Foo.where = undefined x Foo.! y = undefined x Foo... y = undefined --remember ".." is reserved id, e.g. [2..5] {-# LANGUAGE RecursiveDo, BangPatterns #-} module Bar where import Foo hello !x = mdo { y <- Foo.mdo Foo... ({-Foo.-}f x y); return y } {- Haskell 98 -} module Baz where import Foo goodbye x = x ! 12 (Foo.where) lexing as (Foo.wher e) or (Foo . where) does not make me happy. (being a lexer error is a little less bad...) Especially not when the set of keywords is flexible. I don't see any good reason to forbid declaring keywords as identifiers/operators, since it is completely unambiguous, removes an extension-dependence from the lexer and simplifies it (at least the mental lexer); Also I hear that the Haskell98 lexing is (Foo.wher e), which I'm sure no one relies on... Well, that's my humble opinion on what should go into Haskell' on this issue. Isaac