On Wed, Nov 25, 2009 at 2:51 PM, Michael Mossey
I'm fairly new to Haskell, and starting to write some big projects. Previously I used OO exclusively, mostly Python. I really miss the "namespace" capabilities... a class can have a lot of generic method names which may be identical for several different classes because there is no ambiguity.
In my musical application, many "objects" (or in Haskell, data) have a time associated with them. In Python I would have an accessor function called "time" in every class.
So if I have objects/data note1, cursor1, and staff1,
Python: note1.time() cursor1.time() staff1.time()
Haskell needs something like note_time note1 cursor_time cursor1 staff_time staff1
which is a lot more visually disorganized.
What's worse, I have a moderate case of RSI (repetitive strain injury) so I type slowly and depend on abbreviations a lot. I use the souped-up abbreviation capabilities of Emacs. Let's say I have a field/member-variable called orientedPcSet that is used across many classes. In Python, I can create an abbreviation for that and it is useful many times. In Haskell, I might need
someType_orientedPcSet someOtherType_orientedPcSet thirdType_orientedPcSet
which prevents me from using abbreviations effectively (especially the dynamic-completion feature). (It would help to make the underscore not part of word syntax, but that's not ideal.)
So I'm thinking of moving to a scheme in Haskell using modules, most types being defined in their own modules, and doing qualified imports. Generic names like 'time' can be defined in each module w/o clashing. Then I have
Note.time note1 Cursor.time cursor1 Staff.time staff1
This is very useful because I can define abbreviations for the type name and for oft-used accessor function names and these abbrevs are more organized, easier to remember, and easier to combine.
I would be interested in comments... is this a good way to do things? Am I trying too hard to impose OO on Haskell and is there a better way?
That is the way to do what you want and not a bad practice in general. There's nothing particularly OO about namespacing, for example, ML's modules and functors are quite a bit more flexible in this regard than typical OO languages.