Haskell syntax error for where statement [duplicate]

Answer 1

You are using tabs for indentation, so the second definition in the where clause is actually not aligned with the first one. Haskell uses a tab width of 8 spaces, which may be different from your editor, leading to problems like this where the code looks okay, but really isn't.

I strongly recommend that you configure your editor to use spaces only when working with Haskell code.

Answer 2

Some guessing involved since you don’t provide the complete code, but this error could indicate that your line iLength = ... is not properly indented; actually, that the iLength starts to the right of the length = on the line before.

Does your original file use tabs instead of spaces for indentation? If so, be aware that Haskell always interprets a tab as spanning 8 columns. So, e.g.,

<TAB>where length = ...
<TAB><TAB><SPACE><SPACE>iLength = ...

would be interpreted as

        where length = ...
                  iLength = ...

thus causing the error, even though your editor might show the lines properly aligned if it uses 4-column tabs.