On Nov 22, 2007 8:19 AM, Peter Verswyvelen <[EMAIL PROTECTED]> wrote:
> worksFine =
> if True
> then putStrLn "True"
> else putStrLn "False"
This is just an expression, the indentation is inconsequential.
> worksNOT = do
> if True
> then putStrLn "True"
> else putStrLn "False"
The first line, "if True", sets the indentation level of the
statements in the "do" to two spaces. So this is interpreted as
worksNOT = do {
if True ;
then putStrLn "True" ;
else putStrLn "False"
}
Which is of course illegal.
> worksAgain = do
> if True
> then putStrLn "True"
> else putStrLn "False"
Here, the indentation level of the "do" is still two spaces, but then
then and else are at a higher indent than that, so they are
interpreted as part of the preceding expression. The rules are
actually very simple.
Luke
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