C++を使いながらHaskell学習

備忘録も兼ねて ٩(ˊᗜˋ*)و.
##配列の中の数を足す

hairetsuplus.cpp

#include<iostream>
#include<vector>
using namespace std;

int main(){
	vector<int> xs{1,2,3};
	vector<int> ys;
	for(auto x:xs){
		ys.emplace_back(x+10);
	}
	
	for(auto y:ys){
		cout<<y<<endl;
	}
}
```
11
12
13

``````Haskell:hairetsuplus.hs
main = print $ map(+10)[1,2,3]
```
[11,12,13]
##配列の合計値を算出
``````C++:wa.cpp
#include<iostream>
#include<vector>
using namespace std;

int main(){
	vector<int> xs{1,2,3};
	int total = 0;
	for(auto x:xs){
		total += x;
	}
	cout<<total<<endl;
}
```
6

``````Haskell:wa.hs
main = print $ foldr (+) 0 [1,2,3]
```
6

##配列のある数字以上の数を取り出す
``````C++:bignumberinsert.cpp
#include<iostream>
#include<vector>
using namespace std;

int main(){
    vector<int> xs{1,2,3,4,5,6};
    vector<int> ys;
    for(auto x:xs){
        if(x>3){
            ys.emplace_back(x);
        }
    }   

    for(auto y:ys){
        cout<<y<<endl;
    }
}
```
4
5
6

``````Haskell:bignumberinsert.hs
main = print $ filter(>3)[1,2,3,4,5,6]
```
[4,5,6]

##関数をかけあわせる
``````C++:kansuu.cpp
#include<iostream>
#include<vector>
using namespace std;

int f(int x){return x+10;}

int g(int x){return x*x;}

int main(){
	vector<int>xs{1,2,3};
	vector<int>ys;
	for(auto x:xs){
		ys.emplace_back(g(f(x)));
	}
	
	for(auto y:ys){
		cout<<y<<endl;
	}
}
```
121
144
169

``````Haskell:kansuu.hs
f x = x+10

g x = x * x

main = print $ map(g.f)[1,2,3]
```
[121,144,169]