Fmap

[kkazuo]

It's inspired from Haskell's fmap.
An array's fmap returns a new array, and a dictionary's fmap returns a new dictionary not an array.

[mxcl]

Seems that NSArray.fmap is the same as NSArray.map? In which case we should just make it an alias rather than duplicate the code.

[kkazuo]

Partially yes. But fmap preserves container class's mutability. map does not.

NSArray @[x, y, z].fmap(f) returns NSArray @[f(x), f(y), f(z)]
NSMutableArray @[x, y, z].fmap(f) returns NSMutableArray @[f(x), f(y), f(z)]

return type of NSArray.fmapshould be (instancetype *(^)(id)), if I could.

[mxcl]

I think probably this is a bug in map.

[kkazuo]

OK.
NSMutableDictionary.map returns NSArray instead of NSMutableArray.
Do you think this is bug too? or only NSArray.map has bug?

[mxcl]

In the case of the dictionary map it is hard to know if the originating dictionary is mutable or not. I've tried to write such code. So in that case we can just return an NSArray IMO, as it doesn't matter since the type is different anyway.

[kkazuo]

Now, NSArray.fmap is alias of NSArray.map.
And little tweak on NSArray.map.

[kkazuo]

Thank you!