# applicative-numbers: Applicative-based numeric instances

[ bsd3, data, library, numerical ] [ Propose Tags ]

Any applicative functor can be given numeric instances in a boilerplate way. The applicative-numbers package provides an include file that makes it a snap to define these instances. See Data.Numeric.Function for an example.

Instances of Num classes for applicative functors. To be #include'd after defining APPLICATIVE as the applicative functor name and CONSTRAINTS as a list of constraints, which must carry its own trailing comma if non-empty. The APPLICATIVE symbol gets #undef'd at the end of the include file, so that multiple includes are convenient.

For instance,

#define INSTANCE_Ord
#define INSTANCE_Enum

#define APPLICATIVE Vec2
#include "ApplicativeNumeric-inc.hs"

#define APPLICATIVE Vec3
#include "ApplicativeNumeric-inc.hs"

#define APPLICATIVE Vec4
#include "ApplicativeNumeric-inc.hs"


You'll also have to import pure and liftA2 from Control.Applicative and specify the FlexibleContexts language extension (due to an implementation hack).

Some instances are generated only if a corresponding CPP symbol is defined: INSTANCE_Eq, INSTANCE_Ord, INSTANCE_Show, INSTANCE_Enum

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