Graphics.UI.SybWidget.InstanceCreator

Contains functions to automatically create instances from data type definitions.

Documentation

gGenUpTo

Arguments

:: forall a ctx . Data ctx a

=> Proxy ctx

-> Int

Max number of recursions

-> [a]

Generates all possible instances of a, while using no more than n levels of recursion. Each subtype requires another level of recursion. For example:

Branch (Branch Leaf 17) (Leaf 3)

would require 4 levels of recursion. One for the first branch, one for second branch, one for the left Leaf, and one for the Int (the seventeen). The right part of the first branch (Left 3) would be done in two recursions.

createInstance :: forall a ctx. Data ctx a => Proxy ctx -> Maybe a

Creates an instance of a Haskell type. For this to work the compiler must be able to deduce the type from the callee's context.

createInstance' :: forall a ctx. Data ctx a => Proxy ctx -> a -> Maybe a

Like createInstance excepts it uses a phantom type to elicit the correct type to return.

instanceFromConstr

Arguments

:: forall a ctx . Data ctx a

=> Proxy ctx

-> Constr

-> Maybe a

Returns Nothing if it was not possible to create the value.

Creates an instance with a specific constructor.