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In Haskell, I can easily map a list:
map (\x -> 2*x) [1,2] gives me [2,4]. Is there any "mapTuple" function which would work like that?
mapTuple (\x -> 2*x) (1,2) with the result being (2,4).
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Python map object is an iterator, so we can iterate over its elements. We can also convert map object to sequence objects such as list, tuple etc.
A tuple is a fixed-length coupling of values, written in parentheses with the values separated by commas. One way to use this is to pass all parameters into a function as one value, rather than the curried functions we've seen so far.
Use parentheses and commas to create tuples. Use one comma to create a pair. Use more commas to create tuples with more components. Note that it is also possible to declare tuples using in their unsugared form.
map is a function that takes two parameters: a function and a list of elements. The type signature of map is (a -> b) -> [a] -> [b] . The (a -> b) part is the function you pass to map , we will call it f . f takes one value and returns another that may be of a different type.
Here's a rather short point-free solution:
import Control.Monad (join) import Control.Arrow ((***)) mapTuple = join (***) Searching at Hoogle gives no exact matches for (a -> b) -> (a, a) -> (b, b), which is the type you require, but it is pretty easy to do yourself:
mapTuple :: (a -> b) -> (a, a) -> (b, b) mapTuple f (a1, a2) = (f a1, f a2) Note, you will have to define a new function for 3-tuples, 4-tuples etc - although such a need might be a sign, that you are not using tuples like they were intended: In general, tuples hold values of different types, so wanting to apply a single function to all values is not very common.
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