[Haskell-cafe] I miss OO
Michael Mossey
mpm at alumni.caltech.edu
Wed Nov 25 15:51:42 EST 2009
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?
Thanks,
Mike
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