On Wed, 8 Mar 2006, Doaitse Swierstra wrote:
1) it is impossible to explain the precise workings of the rule to a class of first years undergraduates
This is extremely demotivating. I do not want to teach using the following utterances: "If you write your programs in the same style as I do on my slides, you will usually get away with it". Students are perfectly happy to accept that complicated things are complicated, but are not very willing to buy complicated explanations for things which ought to be simple. I furthermore think it is waist of time to to have to go into this in my lectures. I do not think the alternative, in which you always have to write { ; ; } is an option. A language in which every let is followed by a { is plain stupid; just like in Pascal, where each procedure, function, const, var and begin keyword has to be preceded by a (thus superfluous) semicolon.
I found the layout rule trivial to understand the moment I knew about the braces-and-semicolons versions of the constructs and that the layout rule desugars to that with some simple rules. After that it was just a matter of remembering where the braces are on which constructs. I can see it might be a little harder explaining it to a class who haven't seen a braces-and-semicolons language before Haskell though. -- flippa@flippac.org 'In Ankh-Morpork even the shit have a street to itself... Truly this is a land of opportunity.' - Detritus, Men at Arms