How can I add a parameter to this list ?

putIntoList :: a -> [a] 
putIntoList = ?

CodePudding user response：

Add to what list? Your type only specifies one parameter, and a list result. You thus do not add to a list, but rather create a new list from a given value:

putIntoList :: a -> [a]     -- type
putIntoList = \a -> [a]     -- value

is the only thing it can do. Or actually,

putIntoList :: a -> [a]        -- type
putIntoList = \a -> [a,a,a]    -- value

is another possibility. Or any number of repetitions of the same value, which we got as a parameter to this function.

There's thus one more possibility (besides returning an error):

putIntoList :: a -> [a] 
putIntoList = \a -> [ ....

Do finish this definition.