Duh, Sorry. Yes, there was a typo the second one should read
If E is a combination E1 E2 then X is bound in E if and only if X is bound in E1 or is bound in E2. Apologies for that oversight! Mark On 30/12/2010, at 1:21 PM, Antoine Latter wrote: > Was there a typo in your email? Because those two definitions appear > identical. I could be missing something - I haven't read that book. > > Antoine > > On Wed, Dec 29, 2010 at 9:05 PM, Mark Spezzano > <mark.spezz...@chariot.net.au> wrote: >> Hi, >> >> Presently I am going through AJT Davie's text "An Introduction to Functional >> Programming Systems Using Haskell". >> >> On page 84, regarding formal definitions of FREE and BOUND variables he >> gives Defn 5.2 as >> >> The variable X is free in the expression E in the following cases >> >> a) <omitted> >> >> b) If E is a combination E1 E2 then X is free in E if and only if X is free >> in E1 or X is free in E2 >> >> c) <omitted> >> >> Then in Defn 5.3 he states >> >> The variable X is bound in the expression E in the following cases >> >> a) <omitted> >> >> b) If E is a combination E1 E2 then X is free in E if and only if X is free >> in E1 or X is free in E2. >> >> c) <omitted> >> >> Now, are these definitions correct? They seem to contradict each >> other....and they don't make much sense on their own either (try every >> combination of E1 and E2 for bound and free and you'll see what I mean). If >> it is correct then please give some examples of E1 and E2 showing exactly >> why. Personally I think that there's an error in the book. >> >> You can see the full text on Google Books (page 84) >> >> Thanks for reading! >> >> Mark Spezzano >> >> >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe@haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe >> > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
