"Dragon Ball Z Shin Budokai" is an improved version of the PS2 "Dragon Ball Z Battle of Z" game.
Dragon Ball Z Shin Budokai (PSP). Download (Firmware) for Android Apps. 0.0.9.. Download (Firmware) for Android Apps on Google Play.
The Dragon Ball Z Shin Budokai is a title of a japanese video game for the Sony PlayStation Portable console published by Namco Bandai and Nintendo in. It is the 20th game based on the popular anime and is also a part of a sequel to. Download Dragon Ball Z Shin Budokai for Android on Aptoide right now! No extra costs.
User rating for Dragon Ball Z Shin Budokai: 4.12.
Haskell: two SeqCompose instances with different composition
I want to define a common SeqCompose instance, and two specialized ones like this:
instance SeqCompose a b = SeqCompose (a,b) where
s = (s,)
instance SeqCompose (a,b) d = SeqCompose ((a,b),d) where
s = (s,)
This doesn't work, because the compiler complains:
No instance for (SeqCompose c0) arising from a use of `s'
The type variable `c0' is ambiguous
Why? c0 = (a,b)
and I expected that the single a,b would have some sort of uniqueness that the compiler would be able to notice.
The type of s is not determined until later in the type-checking process. This is why you get a type-checking error at this point. The compiler is making a best effort to ensure that there is only one possible way to interpret s, it does not yet know that.
Unfortunately, this isn't at all obvious to the compiler, and as you found out, can lead to all sorts of difficult problems. GHC is trying to help prevent such problems by ensuring that the function is only called with a very specific type, but this only works when type-inference is able to decide which types are allowed in the function.
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