f _ _ = ["x","y","f","g"]
On 4/11/17 11:48 PM, mirone wrote:
Hello everyone!
If I have a list A : ["x", "y", "z"]
and a list B: ["f", "g"].
Here is my question:
What's the simplest way to replace "z" in the list A by list B, and get
["x", "y", "f", "g"] ?
That's a joke, but it really isn't clear what the question means.
One possibility is
f a b = init a ++ b
f [1,2,3,4,5] [9,8,7] => [1,2,3,4,9,8,7]
If you mean that you want to replace "z" by ... wherever it occurs,
something like
-- (f needle straws haystack) replaces each occurrence of needle as
-- an element of haystack with the elements of straws.
f :: Eq t => t -> [t] -> ([t] -> [t])
f needle straws =
concatMap (\straw -> if straw == needle then straws else [straw])
f "z" ["f","g"] ["x","z","y","z"] => ["x","f","g","y","f","g"]
Your question admits of too many generalisations for us to be really
helpful.
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