This module captures annotations on a value, and builds a Capture value. This module has two ways of writing annotations:

Impure: The impure method of writing annotations is susceptible to over-optimisation by GHC - sometimes {-# OPTIONS_GHC -fno-cse #-} will be required.

Pure: The pure method is more verbose, and lacks some type safety.

As an example of the two styles:

 data Foo = Foo {foo :: Int, bar :: Int}

 impure = capture $ Foo {foo = 12, bar = many [1 &= "inner", 2]} &= "top"

 pure = capture_ $ record Foo{} [foo := 12, bar :=+ [atom 1 += "inner", atom 2]] += "top"

Both evaluate to:

 Capture (Ann "top") (Ctor (Foo 12 1) [Value 12, Many [Ann "inner" (Value 1), Value 2]]

Capture a value. Note that if the value is evaluated more than once the result may be different, i.e.

 capture x /= capture x

Add an annotation to a value.

It is recommended that anyone making use of this function redefine it with a more restrictive type signature to control the type of the annotation (the second argument). Any redefinitions of this function should add an INLINE pragma, to reduce the chance of incorrect optimisations.

Create a constructor/record. The first argument should be the type of field, the second should be a list of fields constructed originally defined by := or :=+.

This operation is not type safe, and may raise an exception at runtime if any field has the wrong type or label.