Haskell lists difference
I'm trying make a lists 开发者_开发百科difference. Found directly prelude operator \\\\
that makes lists difference. But errors Not in scope: '\\\\'
occurs. Here is my simple from command line interpreter:
Prelude> ([1,2,3] ++ [5,6]) -- works like expected
[1,2,3,4,5,6]
prelude> ([1,2,3] \\\\ [1,2]) -- erros occurs
<interactive>:1:11: Not in scope: "\\\\"
Thanks for explanation where I make a mistake.
It's \\
, not \\\\
. You also need to import Data.List
.
Prelude List> import Data.List
Prelude List> ([1,2,3] \\ [1,2])
[3]
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