What does nub do in Haskell?

The nub function removes duplicate elements from a list. In particular, it keeps only the first occurrence of each element. (The name nub means ‘essence’.)

How do I use Find in Haskell?

Function find returns the first element of a list that satisfies a predicate, or Nothing, if there is no such element. findIndex returns the corresponding index. findIndices returns a list of all such indices.

What is tail in Haskell?

The tail function in Haskell returns an error when called on an empty list. Modify myTail so that it does handle the case of an empty list by returning the empty list.

What is fromList Haskell?

singleton and fromList appear in several container modules. Typically, singleton returns a container with a single element, and fromList returns a container with all of the elements from the list (modulo key duplication in mappings).

How do you use flip Haskell?

Flip simply takes a function and returns a function that is like our original function, only the first two arguments are flipped. We can implement it like so: flip’ :: (a -> b -> c) -> (b -> a -> c) flip’ f = g.

What does concat do in Haskell?

concat flattens a list of lists into just a list of elements. It will just remove one level of nesting.

What does drop do in Haskell?

O(n) drop n, applied to a Text, returns the suffix of the Text after the first n characters, or the empty Text if n is greater than the length of the Text.

How do I use not in Haskell?

Meanwhile, Haskell use keyword “not” as “logical not”. However, Haskell use “&&” and “||” as logical operators. Obviously, Haskell avoids using “!” to express concepts of “not”, e.g. “not equal” is “/=” but not “!= “.

What does prelude mean in Haskell?

Prelude is a module that contains a small set of standard definitions and is included automatically into all Haskell modules.

How do I use map function in Haskell?

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.

What is cons in Haskell?

Anyway, Cons is just the constructor name — it is an arbitrary name. You can use data List a = Foobar a (List a) …. and name it Foobar , if you wish. Cons is a historic name, though, originating from Lisp. :-: is another arbitrary name for the constructor, except that it can be used infix.