Data.Result

Describing Simulation Results with Type Annotations

Carbon simulations are built up from MonteCarlo actions. A MonteCarlo action describes how to arrive at an observation, but not how to aggregate observations. This functionality is specified with a type annotation telling Haskell which instance of the type family Result should be used.

For example, given a MonteCarlo action, mySim, with type:

mySim :: RandomGen g => MonteCarlo g Bool

We get different results based on the instance of Result chosen:

experimentS mySimulation 100 g :: [Bool]
experimentS mySimulation 100 g :: BoolSumm

class Result r where

Result is the type family used to describe the aggregation techniques to be used in a Monte Carlo simulation. Instances of Result should specify the type of a single observation and how to include one. The value of a Result without any observations should be specified. Additionally, Results should be joinable.

Note that almost all instances of Result will be monoidal.

Associated Types

type Obs r :: *

The type of a single observation

Methods

addObs :: r -> Obs r -> r

How to add a single observation to the result

rjoin :: r -> r -> r

How to join two results together

rzero :: r

The value of a result without any observations

Instances

Result BoolSumm

Result DoubleSumm

NFData a => Result [a]

One common aggregation technique is appending observations to a list. In the interest of preventing thunks from building up, we force deep evaluation of observations.