Updated April 10, 2023
Definition of Haskell Stack
In Haskell we have stack data structure which is also used to store the element inside it. Also to use the stack we have to include libraries into the application it is not present in Haskell. In this section, we will use Data. Stack library, also it provide us so many functions which is used to perform different operations in element present inside it. In Stack data structure we add and delete the element at the top of the stack only, it works in the last in first out manner. In the coming section of the tutorial, we will see the internal working of the stack in detail which will help us to get a clear idea of how to use this while programming in Haskell and also its implementation in detail to get start with.
Syntax:
As we discussed the stack is a data structure like any other programming language, it has main two operations such as push and pop which help us to perform operations of the stack. Let’s take a closer look at the stack syntax for beginners for better understanding see below;
stackNew:: Stack aAs you can see in the above line of syntax we are creating a simple stack by using the keyword ‘stack’ but to implement this we have to use the Data. Stack library into our code. Let’s take a sample piece of syntax for better understanding see below;
e.g. :
stackPush :: Stack a -> a -> Stack aAs you can see in the above line of syntax we are trying to use one of the methods from the Data. Stack library in Haskell. Without this library, it will not work in code. In the coming section of the tutorial, we will see the internal working of the stack in detail and how it functions internally with different types of functions available inside the Data. Stack library.
How Haskell stack works?
As we already know the stack is a data structure available in Haskell which is used to store the elements inside it. This stack works in the same way like any other programming language, but it mainly has two operations which are very important to understand the stack working in detail. In this section, we will see the flow of the stack in Haskell in detail also with the flow chart diagram with all the steps in detail for beginners to understand it better. First, take a look at the flow chart see below;
1) Stack works in the LIFO manner which means last in first out order. This approach suggests or indicted that the element which has entered first will be the last to come out or vice versa in general.
2) In Stack we always remove or add the elements from the one end only. that means this satisfies the LIFO completely here.
3) In the stack we generally use the push and pop method to add r delete the element from the stack.
4) If we have used to push method that ends it will add a new element to the stack.
5) If we use the pop method then it will remove the first element or the available first element from the given stack.
6) After all the operations being performed it will exit.
Now we will see some of the methods which are available inside the Data. Stack package which we can use to perform some operations on the stack, let’s take a closer look for better understanding see below;
1) stackPush: This is the function available inside the Data. Stack we have to have this package into the code.
Basically, this function is used to add a new element to the stack or empty stack we have created. Let’s take a closer look at the syntax fr this function given by the Haskell documentation see below;
e.g. :
stackPush :: Stack a -> a -> Stack aAs you can see it is the official documentation of the stack push declaration given by Haskell.
2) stackNew: This is the function available inside the Data. Stack we have to have this package into the code. Basically, this function is used to create an empty stack. Let’s take a closer look at the syntax for this function given by the Haskell documentation see below;
e.g. :
stack new :: Stack aAs you can see it is the official documentation of the stack push declaration given by Haskell.
3) stack pop: This is the function available inside the Data. Stack we have to have this package into the code. Basically, this function is used to delete an entry from the stack that we have created and it will always be deleted from the top. Let’s take a closer look at the syntax for this function given by the Haskell documentation see below;
e.g. :
stackPop :: Stack a -> Maybe (Stack a, a)As you can see it is the official documentation of the stack push declaration given by Haskell.
4) stackIsEmpty: This is the function available inside the Data. Stack we have to have this package into the code.
Basically, this function is used to check whether the stack is empty or not. Let’s take a closer look at the syntax for this function given by the Haskell documentation see below;
e.g. :
stackIsEmpty :: Stack a -> BoolAs you can see it is the official documentation of stackPush declaration given by Haskell.
5) stackSize: This is the function available inside the Data. Stack we have to have this package into the code. Basically, this function is used to check the size of the stack how many elements present inside it. Let’s take a closer look at the syntax for this function given by the Haskell documentation see below;
e.g. :
stackSize :: Stack a -> NaturalAs you can see it is the official documentation of stackPush declaration given by Haskell.
Now we can see one example of how it works in actuality see below;
stack = [2, 3, 4, 5 ]Suppose we have this stack created with some numbers inserted inside it. So let’s suppose we have inserted 2 then it will be the last to remove because it works in the LIFO manner. after that, we have inserted 3 then if we want to remove them it will remove 3 first then the first inserted element.
Conclusion
By the use of stack, we can store our elements inside it, also easy to use and handle in Haskell. But it is not presented in Haskell directly we have to include the Data. Stack library for this to work otherwise it will not work. These are very easy to use and handle also readable by the developers as well.
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