Haskell parse error on input '='

Question

This is a Quicksort function. But I've got an error at 5:46

--sort function
quicksort [] = []
quicksort (x:xs) = (quicksort lesser) ++[x] ++ (quicksort greater)
                      where lesser = filter (<) xs
                                 greater = filter (>=) xs

What's the problem? It seems that the function is correct.

Due to immutability, this actually isn't a Quicksort function, but that's a discussion for when you're more comfortable with the language. — rtperson
– rtperson, Commented Oct 21, 2011 at 21:08

Adam Wagner · Accepted Answer · 2011-10-21 21:01:58Z

4

It appears you have a simple whitespace error.... lesser and greater need to be indented equally, so that they begin on the same column.

answered Oct 21, 2011 at 21:01

Adam Wagner

16.2k7 gold badges54 silver badges67 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Артём Царионов Over a year ago

But they are intended equally. it's only here they are not equal

Adam Wagner Over a year ago

you must have a tab character somewhere, because when they are not indented equally, that is the exact error I receive.

rtperson Over a year ago

@Артём Царионов - Make sure you're using spaces instead of tabs. You can set this up in your editor if you're worried about your thumbs. When the tabs are gone from your source code, then you'll know if your indentation is correct or not.

Adam Wagner Over a year ago

@Артём Царионов I don't use Windows, so I'm not sure your best option, but I'm sure it's not Notepad. This question may help: stackoverflow.com/questions/734309/haskell-ide-for-windows

Артём Царионов Over a year ago

I've copied this code to program with csort and renamed it. And I've got two errors now - couldn't match expected type Bool for 3rd string and the same error for 4th

|

Collectives™ on Stack Overflow

Haskell parse error on input '='

1 Answer 1

6 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related