Haskell版追加

テストコードないですが、こんなもんで。。。
```
$ for i in ss sss ssbs bbb ssbbb ssbbbb hsbhfhbh bbssp ppp ppsbp ssffpffssp; do echo "$i => $(runghc yakyu.hs $i)"; done
ss => 010,020
sss => 010,020,100
ssbs => 010,020,021,100
bbb => 001,002,003
ssbbb => 010,020,021,022,023
ssbbbb => 010,020,021,022,023,000
hsbhfhbh => 000,010,011,000,010,000,001,000
bbssp => 001,002,012,022,100
ppp => 100,200,000
ppsbp => 100,200,210,211,000
ssffpffssp => 010,020,020,020,100,110,120,200,210,000
```