Safe Haskell	None
Language	Haskell98

Observable

Contents

Creating observables
Other utilities on observables

Description

Netrium is Copyright Anthony Waite, Dave Hetwett, Shaun Laurens 2009-2015, and files herein are licensed |under the MIT license, the text of which can be found in license.txt

Synopsis

Creating observables

data Obs a where Source #

A simple expression language of "observable values". An observable represents is a time-varying value (a function from Time to a value).

Currently there are two types of observables:

condition observables, type Obs Bool
real-valued observables, type Obs Double

Constructors

Const :: (Show a, Eq a) => a -> Obs a
Var :: VarName -> Obs Double
NamedVal :: VarName -> Obs Double
NamedCond :: VarName -> Obs Bool
At :: Time -> Obs Bool
After :: Time -> Obs Bool
Before :: Time -> Obs Bool
UnOp :: UnOp a b -> Obs a -> Obs b
BinOp :: BinOp a a b -> Obs a -> Obs a -> Obs b
IfThen :: Obs Bool -> Obs a -> Obs a -> Obs a

Instances

Eq (Obs a) Source #	Equality
Methods (==) :: Obs a -> Obs a -> Bool # (/=) :: Obs a -> Obs a -> Bool #
Floating (Obs Double) Source #	Floating operations
Methods pi :: Obs Double # exp :: Obs Double -> Obs Double # log :: Obs Double -> Obs Double # sqrt :: Obs Double -> Obs Double # (**) :: Obs Double -> Obs Double -> Obs Double # logBase :: Obs Double -> Obs Double -> Obs Double # sin :: Obs Double -> Obs Double # cos :: Obs Double -> Obs Double # tan :: Obs Double -> Obs Double # asin :: Obs Double -> Obs Double # acos :: Obs Double -> Obs Double # atan :: Obs Double -> Obs Double # sinh :: Obs Double -> Obs Double # cosh :: Obs Double -> Obs Double # tanh :: Obs Double -> Obs Double # asinh :: Obs Double -> Obs Double # acosh :: Obs Double -> Obs Double # atanh :: Obs Double -> Obs Double # log1p :: Obs Double -> Obs Double # expm1 :: Obs Double -> Obs Double # log1pexp :: Obs Double -> Obs Double # log1mexp :: Obs Double -> Obs Double #
Fractional (Obs Double) Source #	Double operations
Methods (/) :: Obs Double -> Obs Double -> Obs Double # recip :: Obs Double -> Obs Double # fromRational :: Rational -> Obs Double #
Num (Obs Double) Source #	Note that you can use ordinary Num operators like `+`, `-`, `*` etc in observable expressions.
Methods (+) :: Obs Double -> Obs Double -> Obs Double # (-) :: Obs Double -> Obs Double -> Obs Double # (*) :: Obs Double -> Obs Double -> Obs Double # negate :: Obs Double -> Obs Double # abs :: Obs Double -> Obs Double # signum :: Obs Double -> Obs Double # fromInteger :: Integer -> Obs Double #
Show (Obs a) Source #	Display tree instances
Methods showsPrec :: Int -> Obs a -> ShowS # show :: Obs a -> String # showList :: [Obs a] -> ShowS #

konst :: (Show a, Eq a) => a -> Obs a Source #

A constant observable.

Named observables

type VarName = String Source #

A variable name

primVar :: VarName -> Obs Double Source #

A named external real-valued observable

Example:

primVar "gas-price"

primCond :: VarName -> Obs Bool Source #

A named external condition observable

var :: VarName -> Obs Double Source #

A named interal contract program variable.

Usually you should use letin rather than this directly.

Time-based observables

type Time = UTCTime Source #

We use a continuous model of time.

mkdate :: Integer -> Int -> Int -> Time Source #

Convenience function to create a time from a date.

at :: Time -> Obs Bool Source #

An observable that becomes true at a single given point in time and is false at all other times.

before :: Time -> Obs Bool Source #

An observable that is true up to a given point in time and is false thereafter.

after :: Time -> Obs Bool Source #

An observable that becomes true after a given point in time and is false prior to that time.

between :: Time -> Time -> Obs Bool Source #

An observable that is true between two given points in time and is false at all other times.

between t1 t2 = time >= t1 && time < t2

Operators

Comparison, logical and numeric operators

(%==) :: Obs Double -> Obs Double -> Obs Bool infix 4 Source #

(%>) :: Obs Double -> Obs Double -> Obs Bool infix 4 Source #

(%>=) :: Obs Double -> Obs Double -> Obs Bool infix 4 Source #

(%<) :: Obs Double -> Obs Double -> Obs Bool infix 4 Source #

(%<=) :: Obs Double -> Obs Double -> Obs Bool infix 4 Source #

(%&&) :: Obs Bool -> Obs Bool -> Obs Bool infixr 3 Source #

(%||) :: Obs Bool -> Obs Bool -> Obs Bool infixr 2 Source #

(%+) :: Obs Double -> Obs Double -> Obs Double infixl 6 Source #

(%-) :: Obs Double -> Obs Double -> Obs Double infixl 6 Source #

(%*) :: Obs Double -> Obs Double -> Obs Double infixl 7 Source #

(%/) :: Obs Double -> Obs Double -> Obs Double infixl 7 Source #

Other observable functions

ifthen :: Obs Bool -> Obs a -> Obs a -> Obs a Source #

if..then..else for observables (returns an observable)

negate :: Num a => a -> a #

Unary negation.

not :: Obs Bool -> Obs Bool Source #

Negate a boolean observable

max :: Obs Double -> Obs Double -> Obs Double Source #

min :: Obs Double -> Obs Double -> Obs Double Source #

abs :: Num a => a -> a #

Absolute value.

Other utilities on observables

Parsing

parseObsCond :: XMLParser (Obs Bool) Source #

XML parser for condition observables

parseObsReal :: XMLParser (Obs Double) Source #

XML parser for real-valued observables

printObs :: Obs a -> Content () Source #

Create XML tags

Evaluating

eval :: Time -> Obs a -> Steps a Source #

Evaluate an observable at a given time

data Steps a Source #

Constructors

NeedNamedVal Time VarName (Double -> Steps a)
NeedNamedCond Time VarName (Bool -> Steps a)
Result a

Instances

Show a => Show (Steps a) Source #
Methods showsPrec :: Int -> Steps a -> ShowS # show :: Steps a -> String # showList :: [Steps a] -> ShowS #

subst :: VarName -> Double -> Obs a -> Obs a Source #

Analysing

isTrue :: Time -> Obs Bool -> Bool Source #

Check if an observable is known to be true at a given point in time, independent of knowledge of any external observables

isFalse :: Time -> Obs Bool -> Bool Source #

Check if an observable is known to be false at a given point in time, independent of knowledge of any external observables

nextTrue :: Time -> Obs Bool -> Maybe Time Source #

The next time that an observable is guaranteed to become true

nextFalse :: Time -> Obs Bool -> Maybe Time Source #

The next time that an observable is guaranteed to become false

evermoreTrue :: Time -> Obs Bool -> Bool Source #

evermoreFalse :: Time -> Obs Bool -> Bool Source #

timeHorizon :: Time -> Obs Bool -> Maybe Time Source #

The time horizon of an condition observable is earliest time that it guaranteed to become true (or Nothing if there is no such time)

earliestTimeHorizon :: Time -> [(Obs Bool, a)] -> Maybe (Time, a) Source #

Return the earliest time horizon of a set of observables and the associate tag of the observable that has the earliest time horizon (or Nothing if none of the observables have a time horizon)

simplifyWithinHorizon :: Time -> Time -> Obs Bool -> Obs Bool Source #