On 9 Aug 2007, at 8:41 am, David Roundy wrote:
I may be stating the obvious here, but I strongly prefer the do syntax. It's nice to know the other also, but the combination of do +indenting makes complicated code much clearer than the nested parentheses that would be required with purely >>= syntax.
Er, what nested parentheses would those be? do e => e do e => e >> rest rest' do p <- e => e >>= \p -> rest rest' do let d => let d in rest rest' We get extra >>, >>=, \, ->, and "in" tokens, but no new parentheses. The example in the Report makes this clear: do putStr "x: " l <- getLine return (words l) desugars to putStr "x: " >> getLine >>= \l -> return (words l) with no extra parentheses. [Not that this actually works in GHC 6; the implied flush isn't done.]