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Someone can explain this coding to me.
[ x*y | x <- [2,5,10], y <- [8,10,11], x*y > 50]
I don't understand the meaning of this | symbol in haskell
744
The @ Symbol is used to both give a name to a parameter and match that parameter against a pattern that follows the @ . It's not specific to lists and can also be used with other data structures.
The == is an operator for comparing if two things are equal. It is quite normal haskell function with type "Eq a => a -> a -> Bool". The type tells that it works on every type of a value that implements Eq typeclass, so it is kind of overloaded.
Backticks make a function an infix operator. This is sometimes a more natural way to write expressions. Parentheses around a binary operator turns it into a two-argument function. This is most useful when you want to pass it as an argument (later).
The ++ operator is the list concatenation operator which takes two lists as operands and "combines" them into a single list.
You should read it as "where" or "such that" -
-- x * y where x is from [2,5,10] and y is from [8,10,11] and x * y > 50
[ x * y | x <- [2,5,10], y <- [8,10,11], x * y > 50]
or, alternatively, if you're familiar with Python and its list comprehensions, you might read it as "for"
-- [x * y for x in [2,5,10] for y in [8,10,11] if x * y > 50]
[x * y | x <- [2,5,10], y <- [8,10,11], x * y > 50]
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