Opaleye.Internal.Unpackspec

Constructors

• Unpackspec (PackMap PrimExpr PrimExpr fields fields')

  An Unpackspec fields fields' allows you to extract and modify a sequence of PrimExprs inside a value of type fields.

  For example, the Default instance of type Unpackspec (Field a, Field b) (Field a, Field b) allows you to manipulate or extract the two PrimExprs inside a (Field a, Field b). The Default instance of type Foo (Field a) (Field b) (Field c) will allow you to manipulate or extract the three PrimExprs contained therein (for a user-defined product type Foo, assuming the makeAdaptorAndInstanceInferrable splice from Data.Profunctor.Product.TH has been run).

  Users should almost never need to create or manipulate Unpackspecs. Typically they will be created automatically by the Default instance. If you really need to you can create Unpackspecs by hand using unpackspecField and the Profunctor, ProductProfunctor and SumProfunctor operations.