Module Control.DeepSeq

This module provides an overloaded function, deepseq, for fully evaluating data structures (that is, evaluating to \"Normal Form\").

deepseq differs from seq as it traverses data structures deeply, for example, seq will evaluate only to the first constructor in the list:

 > [1,2,undefined] `seq` 3
 3

While deepseq will force evaluation of all the list elements:

 > [1,2,undefined] `deepseq` 3
 frege.runtime.Undefined: undefined

Another common use is to ensure any exceptions hidden within lazy fields of a data structure do not leak outside the scope of the exception handler, or to force evaluation of a data structure in one thread, before passing to another thread (preventing work moving to the wrong threads).

Imports

• import frege.Prelude as Prelude
• import Prelude.PreludeArrays as PreludeArrays
• import Prelude.PreludeBase as PreludeBase
• import Prelude.PreludeDecimal as PreludeDecimal
• import Prelude.PreludeIO as PreludeIO
• import Prelude.PreludeList as PreludeList
• import Prelude.PreludeMonad as PreludeMonad
• import Prelude.PreludeText as PreludeText
• import Java.util.Regex as Regexp
• import Data.Tree as Tree

Table of Content

• Definitions

  class NFData α

  deepseq ∷ NFData α ⇒ α → β → β

  $!! ∷ NFData α ⇒ (α → β) → α → β

  force ∷ NFData α ⇒ α → α

• Instances

  instance NFData ()

  instance (NFData a, NFData b) ⇒ NFData (a, b)

  instance (NFData a, NFData b, NFData c) ⇒ NFData (a, b, c)

  instance (NFData a, NFData b, NFData c, NFData d) ⇒ NFData (a, b, c, d)

  instance (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5) ⇒ NFData (a1, a2, a3, a4, a5)

  instance (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6) ⇒ NFData (a1, a2, a3, a4, a5, a6)

  instance (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6, NFData a7) ⇒ NFData (a1, a2, a3, a4, a5, a6, a7)

  instance (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6, NFData a7, NFData a8) ⇒ NFData (a1, a2, a3, a4, a5, a6, a7, a8)

  instance (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6, NFData a7, NFData a8, NFData a9) ⇒ NFData (a1, a2, a3, a4, a5, a6, a7, a8, a9)

  instance NFData (a→b)

  instance NFData Bool

  instance NFData Char

  instance NFData Double

  instance (NFData α, NFData β) ⇒ NFData (α | β)

  instance NFData Float

  instance NFData Int

  instance NFData Integer

  instance NFData Long

  instance NFData α ⇒ NFData (Maybe α)

  instance NFData String

  instance NFData α ⇒ NFData (Tree α)

  instance NFData α ⇒ NFData [α]

• Functions and Values by Type

Definitions

class NFData α

A class of types that can be fully evaluated.

Known Instances

Int, (), ->, (,,,,), (,,), (,), (,,,), (,,,,,,), (,,,,,), (,,,,,,,), (,,,,,,,,), Char, Bool, Either, Double, Float, StringJ, Long, Integer, Maybe, [], Tree.Tree

Member Functions

rnf ∷ NFData α ⇒ α → ()

NFData.rnf should reduce its argument to normal form (that is, fully

evaluate all sub-components), and then return ().

deepseq ∷ NFData α ⇒ α → β → β

Fully evaluates a and returns b.

deepseq: fully evaluates the first argument, before returning the second.

The name deepseq is used to illustrate the relationship to seq: where seq is shallow in the sense that it only evaluates the top level of its argument, deepseq traverses the entire data structure evaluating it completely.

deepseq can be useful for forcing pending exceptions, eradicating space leaks, or forcing lazy I/O to happen. It is also useful in conjunction with parallel Strategies (see the parallel package).

$!! ∷ NFData α ⇒ (α → β) → α → β

the deep analogue of $!. In the expression f $!! x, x is

fully evaluated before the function f is applied to it.

force ∷ NFData α ⇒ α → α

a variant of deepseq that is useful in some circumstances:

 force x = x `deepseq` x

force x fully evaluates x, and then returns it. Note that force x only performs evaluation when the value of force x itself is demanded, so essentially it turns shallow evaluation into deep evaluation.

Instances

instance NFData ()

Member Functions

rnf ∷ () → ()

inherited from NFData.rnf

instance (NFData a, NFData b) ⇒ NFData (a, b)

• ------------------------------------------------------------------------

Member Functions

rnf ∷ (NFData β, NFData α) ⇒ (β, α) → ()

instance (NFData a, NFData b, NFData c) ⇒ NFData (a, b, c)

Member Functions

rnf ∷ (NFData β, NFData γ, NFData α) ⇒ (β, γ, α) → ()

instance (NFData a, NFData b, NFData c, NFData d) ⇒ NFData (a, b, c, d)

Member Functions

rnf ∷ (NFData γ, NFData δ, NFData β, NFData α) ⇒ (γ, δ, β, α) → ()

instance (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5) ⇒ NFData (a1, a2, a3, a4, a5)

Member Functions

rnf ∷ (NFData δ, NFData ε, NFData β, NFData γ, NFData α) ⇒ (δ, ε, β, γ, α) → ()

instance (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6) ⇒ NFData (a1, a2, a3, a4, a5, a6)

Member Functions

rnf ∷ (NFData δ, NFData ε, NFData γ, NFData ζ, NFData β, NFData α) ⇒ (δ, ε, γ, ζ, β, α) → ()

instance (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6, NFData a7) ⇒ NFData (a1, a2, a3, a4, a5, a6, a7)

Member Functions

rnf ∷ (NFData ε, NFData ζ, NFData δ, NFData η, NFData β, NFData γ, NFData α) ⇒ (ε, ζ, δ, η, β, γ, α) → ()

instance (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6, NFData a7, NFData a8) ⇒ NFData (a1, a2, a3, a4, a5, a6, a7, a8)

Member Functions

rnf ∷ (NFData ζ, NFData η, NFData ε, NFData θ, NFData γ, NFData δ, NFData β, NFData α) ⇒ (ζ, η, ε, θ, γ, δ, β, α) → ()

instance (NFData a1, NFData a2, NFData a3, NFData a4, NFData a5, NFData a6, NFData a7, NFData a8, NFData a9) ⇒ NFData (a1, a2, a3, a4, a5, a6, a7, a8, a9)

Member Functions

rnf ∷ (NFData η, NFData θ, NFData ζ, NFData ι, NFData δ, NFData ε, NFData β, NFData γ, NFData α) ⇒ (η, θ, ζ, ι, δ, ε, β, γ, α) → ()

instance NFData (a→b)

This instance is for convenience and consistency with seq.

This assumes that WHNF is equivalent to NF for functions.

Member Functions

rnf ∷ (α→β) → ()

instance NFData Bool

Member Functions

rnf ∷ Bool → ()

inherited from NFData.rnf

instance NFData Char

Member Functions

rnf ∷ Char → ()

inherited from NFData.rnf

instance NFData Double

Member Functions

rnf ∷ Double → ()

inherited from NFData.rnf

instance (NFData α, NFData β) ⇒ NFData (α | β)

Member Functions

rnf ∷ (NFData β, NFData α) ⇒ (β | α) → ()

instance NFData Float

Member Functions

rnf ∷ Float → ()

inherited from NFData.rnf

instance NFData Int

Member Functions

rnf ∷ Int → ()

inherited from NFData.rnf

instance NFData Integer

Member Functions

rnf ∷ Integer → ()

inherited from NFData.rnf

instance NFData Long

Member Functions

rnf ∷ Long → ()

inherited from NFData.rnf

instance NFData α ⇒ NFData (Maybe α)

Member Functions

rnf ∷ NFData α ⇒ Maybe α → ()

instance NFData String

Member Functions

rnf ∷ String → ()

inherited from NFData.rnf

instance NFData α ⇒ NFData (Tree α)

Member Functions

rnf ∷ NFData α ⇒ Tree α → ()

instance NFData α ⇒ NFData [α]

Member Functions

rnf ∷ NFData α ⇒ [α] → ()

Functions and Values by Type

String → ()

NFData_String.rnf

() → ()

NFData_().rnf

Bool → ()

NFData_Bool.rnf

Char → ()

NFData_Char.rnf

Double → ()

NFData_Double.rnf

Float → ()

NFData_Float.rnf

Int → ()

NFData_Int.rnf

Integer → ()

NFData_Integer.rnf

Long → ()

NFData_Long.rnf

NFData α ⇒ Tree α → ()

NFData_Tree.rnf

NFData α ⇒ Maybe α → ()

NFData_Maybe.rnf

NFData α ⇒ [α] → ()

NFData_[].rnf

NFData α ⇒ α → ()

NFData.rnf

NFData α ⇒ α → α

force

(α→β) → ()

NFData_->.rnf

NFData α ⇒ (α → β) → α → β

$!!

NFData α ⇒ α → β → β

deepseq

(NFData β, NFData α) ⇒ (β, α) → ()

NFData_(,).rnf

(NFData β, NFData α) ⇒ (β | α) → ()

NFData_Either.rnf

(NFData β, NFData γ, NFData α) ⇒ (β, γ, α) → ()

NFData_(,,).rnf

(NFData γ, NFData δ, NFData β, NFData α) ⇒ (γ, δ, β, α) → ()

NFData_(,,,).rnf

(NFData δ, NFData ε, NFData β, NFData γ, NFData α) ⇒ (δ, ε, β, γ, α) → ()

NFData_(,,,,).rnf

(NFData δ, NFData ε, NFData γ, NFData ζ, NFData β, NFData α) ⇒ (δ, ε, γ, ζ, β, α) → ()

NFData_(,,,,,).rnf

(NFData ε, NFData ζ, NFData δ, NFData η, NFData β, NFData γ, NFData α) ⇒ (ε, ζ, δ, η, β, γ, α) → ()

NFData_(,,,,,,).rnf

(NFData ζ, NFData η, NFData ε, NFData θ, NFData γ, NFData δ, NFData β, NFData α) ⇒ (ζ, η, ε, θ, γ, δ, β, α) → ()

NFData_(,,,,,,,).rnf

(NFData η, NFData θ, NFData ζ, NFData ι, NFData δ, NFData ε, NFData β, NFData γ, NFData α) ⇒ (η, θ, ζ, ι, δ, ε, β, γ, α) → ()

NFData_(,,,,,,,,).rnf