순수 함수형 언어.

다음 3개의 예제 파일을 작성한 후 빌드하면 된다.

• hello.hs

    module Hello where
  
    foreign export ccall add :: Int -> Int -> Int
    foreign export ccall multiply :: Int -> Int -> Int
  
    add :: Int -> Int -> Int
    add x y = x + y
  
    multiply :: Int -> Int -> Int
    multiply x y = x * y
  

• main.cpp

    #include <iostream>
    #include "hello_stub.h"
    using namespace std;
  
    int main(int argc, char** argv)
    {
        hs_init(&argc, &argv);
  
        cout << "3 + 7 = " << add(3, 7) << endl;
        cout << "3 * 7 = " << multiply(3, 7) << endl;
  
        hs_exit();
  
        return 0;
    }
  

• Makefile

    build : hello.o main.o
        ghc -no-hs-main -o main main.o hello.o -lstdc++
  
    main.o:
        g++ -c main.cpp -I/usr/lib/ghc-8.6.4/include
  
    hello.o:
        ghc -c hello.hs
  
    clean:
        rm  hello.hi \
            hello.o \
            hello_stub.h \
            main.o \
            main