Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
Synopsis
- data CostRose = CostRose !CostingInteger ![CostRose]
- singletonRose ∷ CostingInteger → CostRose
- class ExMemoryUsage a where
- memoryUsage ∷ a → CostRose
- flattenCostRose ∷ CostRose → CostStream
- newtype NumBytesCostedAsNumWords = NumBytesCostedAsNumWords {}
- newtype IntegerCostedLiterally = IntegerCostedLiterally {}
- newtype ListCostedByLength a = ListCostedByLength {
- unListCostedByLength ∷ [a]
Documentation
A lazy tree of costs. Convenient for calculating the costs of values of built-in types, because
they may have arbitrary branching (in particular a Data
object can contain a list of Data
objects inside of it).
CostRose
gets collapsed to a lazy linear structure down the pipeline, so that we can
stream the costs to the outside where, say, the CEK machine picks them up one by one and handles
somehow (in particular, subtracts from the remaining budget).
singletonRose ∷ CostingInteger → CostRose Source #
Create a CostRose
containing a single cost.
class ExMemoryUsage a where Source #
memoryUsage ∷ a → CostRose Source #
Instances
newtype NumBytesCostedAsNumWords Source #
When invoking a built-in function, a value of type NumBytesCostedAsNumWords
can be used transparently as a built-in Integer but with a different size
measure: see Note [Integral types as Integer]. This is required by the
integerToByteString
builtin, which takes an argument w
specifying the
width (in bytes) of the output bytestring (zero-padded to the desired size).
The memory consumed by the function is given by w
, *not* the size of w
.
The NumBytesCostedAsNumWords
type wraps an Int w
in a newtype whose
ExMemoryUsage
is equal to the number of eight-byte words required to
contain w
bytes, allowing its costing function to work properly. We also
use this for replicateByte
. If this is used to wrap an argument in the
denotation of a builtin then it *MUST* also be used to wrap the same argument
in the relevant budgeting benchmark.
Instances
newtype IntegerCostedLiterally Source #
A wrapper for Integer
s whose "memory usage" for costing purposes is the
absolute value of the Integer
. This is used for costing built-in functions
such as shiftByteString
and rotateByteString
, where the cost may depend
on the actual value of the shift argument, not its size. If this is used to
wrap an argument in the denotation of a builtin then it *MUST* also be used
to wrap the same argument in the relevant budgeting benchmark.
Instances
newtype ListCostedByLength a Source #
A wrappper for lists whose "memory usage" for costing purposes is just the length of the list, ignoring the sizes of the elements. If this is used to wrap an argument in the denotation of a builtin then it *MUST* also be used to wrap the same argument in the relevant budgeting benchmark.