On Apr 21, 2005, at 3:47 PM, SCOTT J. wrote:Hi, I'm beginning to study Haskell, For the following a = [1,2,3] b = "there" do x <- a y <- b return (x , y) Winhugs cannot run it. Gives Syntax error in input (unexpected backslash ( lambda))
Your problem is that you're using monads to grab the contents of a and b, while a and b are not monadic... You probably if you're only just setting out don't want to pay attention to any of the do notation or monadic code. To get the result it looks like you want, all you need to do is this:
(a, b)
you can then define this as a new constant:
c = (a, b)
Hope that helps
Bob
On the other hand, perhaps he wanted all possible combinations of values in the lists a and b. Since a list is a monad, this, for example, works fine:
a = [1,2,3]
b = "there"
abs = do x <- a
y <- b
return (x,y)In Hugs: abs ==> [(1,'t'),(1,'h'),(1,'e'),(1,'r'),(1,'e'),(2,'t'),(2,'h'),(2,'e'),(2,'r'),(2,'e') ,(3,'t'),(3,'h'),(3,'e'),(3,'r'),(3,'e')]
-Paul
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