Updated April 10, 2023
Introduction to Haskell take function
We have one function defined in Haskell which is used to take the values from the existing list or it simply takes the value from the existing values available and creates a new list of the variable for us. We have to specify the number of values we want into the resultant list, from the existing or the original array or list we have. Also, we can use the existing functions from the Haskell library which is used to create the list or array, after that we can take the values from that also. In the coming section of the tutorial, we will discuss more the internal working, usage, and implementation of the take function in detail for beginners to understand it better and use it efficiently when required.
Syntax
As we already discussed take is a function in Haskell, which is used to take values from the existing data structure. To use this we do not require import any library because it is an in-built Haskell function that can be used directly. Let’s take a closer look at the syntax of the take function available in Haskell which will make it easier to use for beginners see below;
take param1 [param2]As you can see in the above lines of syntax this function takes two parameters as the input param. Let’s take a look at the practice piece of code syntax which will make it some more clear to understand see below;
e.g. :
take 2 [1,2 , 2]
As you can see it is very easy to use. In the coming section of the tutorial, we will see its internal working in detail which will make it better to understand for because to start with.
How to use take function in Haskell?
As of now we already know the take function is used in Haskell to take some values out based on the parameter we pass. This function usually takes two parameters as the input param, which we will discuss in the coming section of the tutorial. Take function is an in-built function in Haskell so that it can be used directly without any import statement, dependency, or any external library. Also on the other hand this function is very easy to use and has very clean syntax as well. In this section first, we will see the function signature given by the Haskell for take function let’s get started for better understanding see below;
Method signature:
1) Int -> [a] -> [a]: This is the type of signature of the take function given by the official documentation by the Haskell website. As you can see it is easy and very much readable by the developers as well. Now we will see the module in which this function present and how we can access it inside our program written in Haskell. Let’s get started for better usage and implementation see below;
2) Module: If we talk about the module which contains this function then it is called as ‘ Prelude’ module. Which is the default module in Haskell, and it contains all the necessary functions which is required to start coding in Haskell, we can call it a basic module of Haskell like we have in other languages.
3) Now we will discuss the parameter and its syntax in more details which will give the idea of how we can ass the para to get the desired values as the result we want to see below;
e.g. :
take param1 [param2]
As you can see in the above line of code we have two parameters passed using the take function. Also to use the take function we have just simply sued the ‘take’ keyword at the starting of the params we passed. Let’s get started with the parameter details see below;
a) param 1 or value: Here the first para in the take function is responsible or used to represent the number of values that we want to take out from the original array or list or etc. This param will always return us the same number of elements that we pass here from the array we have. Let’s take an example for instance;
e.g. take 3 [] : So this will return us the resultant array or list contains only three values from the original one.
b) param 2 or value 2 : Here the second param of the take function is used to pass the array or list variable from which we want to create a new list or array contain the desired values. It will always represent the original pram to be passed. Let’s take an example to get better ideas to see below;
e.g. take 3 [1, 2, 2 ] : The second param that we have passed here is the original variable form which it will return us the result.
Things to remembered while using take function in Haskell which are as follows;
1) This is present inside the Prelude module in Haskell.
2) It can be used with any type of data type which is available in Haskell, but always remembered the first param will always be an integer type.
3) But the second param can be of any type irrespective of the first integer passed.
4) Always return us the new list or array as the result in return.
Example of Haskell take function
1) Simple example is to show the usage and implementation of the take function, for beginners.
Code:
main = do
print("Demo to show take function Haskell !!")
let list1 = [10, 20, 30, 40 , 50 , 60, 70]
let list2 = [1, 2, 3, 4, 5, 6, 7, 8, 9]
let list3 = [1.1, 2.2, 3.3, 4.4 , 5.5, 6.6, 7.7]
let list4 = [35, 68, 10, 67, 69, 25, 67, 23]
let list5 = ["A1", "B2", "C3", "D4", "E5"]
let list6 = ["hello1", "hello 2", "hello 3", "hello 4"]
let list7 = [10, 20, 30, 40 , 50 , 60, 70]
print("using the function take here to get the values !!")
let result1 = take 1 list1
let result2 = take 5 list2
let result3 = take 0 list3
let result4 = take 3 list4
let result5 = take 4 list5
let result6 = take 2 list6
let result7 = take 6 list7
print("print the result ")
print("result one is ", result1)
print("result one is ", result2)
print("result one is ", result3)
print("result one is ", result4)
print("result one is ", result5)
print("result one is ", result6)
print("result one is ", result7)Output:
Conclusion
As we have seen this function in Haskell is very easy to use and handle, also very readable to the developers. we do not require to import anything before using this because it is available inside the Prelude module of Haskell which is very easy to access in Haskell programming.
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