小编Jak*_*lin的帖子

当我使用-Wall选项编译时,我收到以下错误.

ghc -o -Wall polycake polycake.hs

当我不使用该选项时,我的代码编译正常并按预期运行.这是什么意思？

<no location info>: error:
    module ‘main:Polycake’ is defined in multiple files: polycake.hs
                                                         polycake.hs

我试图推理如何将命令式样式程序转换为像Haskell这样的功能性程序.

功能是:

void calcPerim(point polycake[], int v, int y, double *perim1, double *perim2){
    int next = 0;
    int index = 0;
    point points[2];
    *perim1 = 0.0;
    *perim2 = 0.0;

    for(int i = 0; i < v; i++)
    {
        next = (i + 1) % v;
        if(polycake[i].y < y && polycake[next].y < y)
            (*perim1) += distance(polycake[i], polycake[next]);
        else if(polycake[i].y > y && polycake[next].y > y)
            (*perim2) += distance(polycake[i], polycake[next]);
        else
        {
            points[index] = intersectPoint(polycake[i], polycake[next], y);
            if(polycake[i].y < y)
            {
                (*perim1) …