On Sun, Feb 14, 2010 at 3:20 PM, Daniel Fischer wrote:

Am Sonntag 14 Februar 2010 20:54:54 schrieb John Moore:

...

Hi all,          I must be doing something wrong with my tabs. Because this keeps telling me parse error. Can some one see if it is indentation. I'm sending a file so as you'll be able to see what going on. If I copy it here it can appear wrong the difference is with the Var expression.

John

First of all, *don't mix tabs and spaces for indentation* (best, don't use tabs at all).

I find the latter a bit too restrictive, especially since I use a text editor that is a glorified version of ed. Hitting the spacebar 19 times is too much to ask of me. And as such, I am occasionally forced to do something when a tab doesn't get me past the word `where' or `let', but isn't that the majority of what Layout specifies? Is there a good answer for caveman programmers who like ed and tabs?

It's

evalStep d (Var x)     = case x of        (Val a) ->case x of          (Val b) ->(lookup x d)          if (isJust m_e)then           evalStep(lookup x d)           else            fail "Error in expression -- no definition for variable!"

The "if ... " is aligned with (Val b), so GHC tries to parse it as a pattern. But if-expressions aren't patterns, so you get a parse error.

But the code doesn't really make sense (and isn't well typed) anyway. You probably want something like

evalStep d (Var x)    = case lookup x d of        Just e -> e        Nothing -> error "Error in expression -- no definition for variable!"

for that. _______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners

On Sun, Feb 14, 2010 at 4:46 PM, Stephen Blackheath [to Haskell-Beginners] wrote:

Jorden,

Cave persons such as yourself can use tabs as long as your tab size is 8 characters.  This is "hard-coded" into the Haskell 98 specification.

My editor, being made of sticks, some rocks, and the jawbone of an ass, just puts in a tab character. The graphical representation of a tab character expands from the insertion point to the nearest multiple of 8 characters, but that has no bearing on the file contents. Also, there are situations when a tab-boundary is not enough. What is the correct course of action here? Currently, I usually try to change the line to spaces, or if I'm lazy, I'll put spaces after tabs, which I don't feel good about. My editor knows enough to indent the next line the same amount.

Steve

Jorden Mauro wrote:

...

...

First of all, *don't mix tabs and spaces for indentation* (best, don't use tabs at all).

I find the latter a bit too restrictive, especially since I use a text editor that is a glorified version of ed. Hitting the spacebar 19 times is too much to ask of me.

And as such, I am occasionally forced to do something when a tab doesn't get me past the word `where' or `let', but isn't that the majority of what Layout specifies?

Is there a good answer for caveman programmers who like ed and tabs?

On Feb 14, 2010, at 6:00 PM, Magnus Therning wrote:

On 14/02/10 22:05, Jorden Mauro wrote:

...

On Sun, Feb 14, 2010 at 4:46 PM, Stephen Blackheath [to Haskell-Beginners] wrote:

...

Jorden,

Cave persons such as yourself can use tabs as long as your tab size is 8 characters. This is "hard-coded" into the Haskell 98 specification.

My editor, being made of sticks, some rocks, and the jawbone of an ass, just puts in a tab character. The graphical representation of a tab character expands from the insertion point to the nearest multiple of 8 characters, but that has no bearing on the file contents.

Sure it does, the bearing is that there's a tab character there. ;-)

If I put one.

...

Also, there are situations when a tab-boundary is not enough. What is the correct course of action here?

Other people have already suggested it: change editor.

Not happening. Sam is sublime.

Please let us know if there is *any* good reason for anyone to be using such a limited editor in the 21st century.

Structural regexes. Size. Remote editing. Simplicity of code, UI, etc. Lack of bugs. Orthogonality. Performance. (Sam handles dozens of megabyte-sized files, even on a remote machine, without batting an eye, even during regex commands)

...

Currently, I usually try to change the line to spaces, or if I'm lazy, I'll put spaces after tabs, which I don't feel good about. My editor knows enough to indent the next line the same amount.

From this it sounds like you aren't using such a stone age editor after all.

I assure you, I am. It has exactly only 33 commands. Give it a spin, I doubt you'll like it. It's not ed, but does have a GUI -- a verrry simple one.

Are you sure you can't get it to also convert tabs to spaces?

Not without reprogramming it. Of course, I could convert files by hand, but I could just as easily use spaces. I just thought tabs were acceptable. I was a contientious objector in the Tabs or Spaces War. Is just using spaces the Haskell Caveman Solution?

/M

-- Magnus Therning (OpenPGP: 0xAB4DFBA4) magnus＠therning．org Jabber: magnus＠therning．org http://therning.org/magnus identi.ca|twitter: magthe

_______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners

Am Sonntag 14 Februar 2010 22:30:27 schrieb Jorden Mauro:

On Sun, Feb 14, 2010 at 3:20 PM, Daniel Fischer

wrote:

...

Am Sonntag 14 Februar 2010 20:54:54 schrieb John Moore:

...

Hi all,          I must be doing something wrong with my tabs. Because this keeps telling me parse error. Can some one see if it is indentation. I'm sending a file so as you'll be able to see what going on. If I copy it here it can appear wrong the difference is with the Var expression.

John

First of all, *don't mix tabs and spaces for indentation* (best, don't use tabs at all).

I find the latter a bit too restrictive, especially since I use a text editor that is a glorified version of ed.

Okay: Whyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy? Isn't there some editor which allows you to configure the tab settings but still is whatever-you-like-about-ed enough for you to use?

Hitting the spacebar 19 times is too much to ask of me.

And as such, I am occasionally forced to do something when a tab doesn't get me past the word `where' or `let', but isn't that the majority of what Layout specifies?

Is there a good answer for caveman programmers who like ed and tabs?

Never change your tab-width.

On Sun, Feb 14, 2010 at 04:30:27PM -0500, Jorden Mauro wrote:

On Sun, Feb 14, 2010 at 3:20 PM, Daniel Fischer wrote:

...

Am Sonntag 14 Februar 2010 20:54:54 schrieb John Moore:

...

Hi all,          I must be doing something wrong with my tabs. Because this keeps telling me parse error. Can some one see if it is indentation. I'm sending a file so as you'll be able to see what going on. If I copy it here it can appear wrong the difference is with the Var expression.

John

First of all, *don't mix tabs and spaces for indentation* (best, don't use tabs at all).

I find the latter a bit too restrictive, especially since I use a text editor that is a glorified version of ed. Hitting the spacebar 19 times is too much to ask of me.

And as such, I am occasionally forced to do something when a tab doesn't get me past the word `where' or `let', but isn't that the majority of what Layout specifies?

Is there a good answer for caveman programmers who like ed and tabs?

Another good answer is to use explicit curly braces and semicolons so you don't have to rely on layout. -Brent