37 lines
671 B
Markdown
37 lines
671 B
Markdown
|
---
|
||
|
|
title: map function
|
||
|
|
---
|
||
|
|
|
||
|
|
## `map` function
|
||
|
|
|
||
|
|
The `map` function is a built-in haskell's function that maps a function to each element of a list and return a new list
|
||
|
|
with the result. Graphically, it would look like this.
|
||
|
|
```haskell
|
||
|
|
map f [1,2,3,4]
|
||
|
|
-- [f 1, f 2, f 3, f 4]
|
||
|
|
```
|
||
|
|
|
||
|
|
## Signature of `map`
|
||
|
|
|
||
|
|
The signature of the map function is as follows
|
||
|
|
```haskell
|
||
|
|
map :: (a -> b) -> [a] -> [b]
|
||
|
|
```
|
||
|
|
|
||
|
|
## Examples
|
||
|
|
```haskell
|
||
|
|
map succ [1..5]
|
||
|
|
-- [2,3,4,5,6]
|
||
|
|
|
||
|
|
let sample = [(1, 2), (3, 1), (4, 10)]
|
||
|
|
map fst sample
|
||
|
|
-- [1,3,4]
|
||
|
|
|
||
|
|
map snd sample
|
||
|
|
-- [2,1,10]
|
||
|
|
|
||
|
|
import Data.Char (toLower) # to get the toLower
|
||
|
|
map toLower "HELLO WORLD HASKELL RULEZ!"
|
||
|
|
-- "hello world haskell rulez!"
|
||
|
|
```
|