strict-types

This package provides a type-level predicate Strict and two pattern synonyms IsStrict and 'Rnf' to constrain value strictness.

The Rnf pattern

The 'Rnf' pattern matches every value of a type with an 'NFData' instance, forcing it to rigid normal form before binding it.

> Rnf [trace "1" 1, trace "2" 2]

> IsStrict (False)
False
> IsStrict (Identity False)
Identity False
> IsStrict (Identity (Just False))

<interactive>:1:1: error:
    • Maybe Bool has an unnamed lazy field in constructor Just
    • In the expression: IsStrict (Identity (Just False))
      In an equation for ‘it’: it = IsStrict (Identity (Just False))