lines function not working as expected

Question

In Prelude, unlines work as expected. Below is the example

GHCi>unlines ["aa","bb","bb"] "aa\nbb\nbb\n"

But why does lines not work. Even the type signature says that it can only take numbers.

GHCi>:t lines lines :: Num t => [t]

So, if I try

GHCi>lines "aa\nbb\nbb\n"

why do I get an error? Is there a lines that I need to import?

Regards,

What does GHCi>:i lines give you? That should show where the lines you're seeing is defined. — Chad Gilbert
– Chad Gilbert, Commented Mar 7, 2017 at 14:42
In GHCi it says lines :: String -> [String]. So you have imported a different `lines. — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Mar 7, 2017 at 14:44
Yes mine shows GHCi>:i lines lines :: Num t => [t] -- Defined at <interactive>:14:1. Can you please tell me how I can get the correct one? — Srinivas
– Srinivas, Commented Mar 7, 2017 at 14:49
When GHCi says "Defined at <interactive>:14:1", it means that lines was re-defined in GHCi (input line 14). Hence, you are not using the standard lines. — chi
– chi, Commented Mar 7, 2017 at 15:55

mathk · Accepted Answer · 2017-03-07 14:44:37Z

Are you sure that you are not shadowing the lines function:

:t lines lines :: String -> [String]

Make sure you have not define a lines variable. As @ChadGilbert mention you can use :i

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