Make use of DSL Grammar

Binary AND operator

Keyword: and

And works the same way it does it other languages. Hence following observations.

falseIdentity and trueIdentity == falseIdentity

falseIdentity and falseIdentity == falseIdentity

trueIdentity and trueIdentity == trueIdentity

trueIdentity and falseIdentity == falseIdentity

Here we are using == to show their equality.

Value declaration operator

Keywords: val

Symbols: =

Value declaration lets you modularize things to make your DSL. A DSL only using the and operator and val operator appears as follows:

val rule1= falseIdentity and trueIdentity and trueIdentity

val rule2= trueIdentity and trueIdentity and trueIdentity

rule1 and rule2

The above expression evaluates to false.

Binary OR operator

The or operator works the same way it does it other languages.

falseIdentity or trueIdentity == trueIdentity

falseIdentity or falseIdentity == falseIdentity

trueIdentity or trueIdentity == trueIdentity

trueIdentity or falseIdentity == trueIdentity

Let's expand our DSL to use or as follows.

val rule1= falseIdentity and trueIdentity and trueIdentity

val rule2= trueIdentity and trueIdentity and trueIdentity

val rule3=rule1 and rule2

rule3 or trueIdentity

The above expression evaluates to true.

Unary Not operator

not negates value of a behaviour ( from true to false and vice versa). Hence following observations.

not(falseIdentity) == trueIdentity

not(trueIdentity) == falseIdentity

Use the not operator as follows.

val rule1= falseIdentity and trueIdentity and trueIdentity

val rule2= trueIdentity and trueIdentity and trueIdentity

val rule3=rule1 and rule2

val rule4=rule3 or trueIdentity

rule4 and not(falseIdentity)

The above expression evaluates to true.

All operator

all takes a list of behaviours and evaluates to true only if all of the behaviours evaluate to true.

all(falseIdentity) == falseIdentity

all(falseIdentity,falseIdentity) == falseIdentity

all(trueIdentity) == trueIdentity

all(trueIdentity,trueIdentity) == trueIdentity

all(trueIdentity,falseIdentity) == falseIdentity

all(falseIdentity,........) == falseIdentity

Use the all operator as follows.

val rule1= falseIdentity and trueIdentity and trueIdentity

val rule2= trueIdentity and trueIdentity and trueIdentity

val rule3=rule1 and rule2

val rule4=rule3 or trueIdentity

val rule5=rule4 and not(falseIdentity)

all(rule5,trueIdentity)

The above expression evaluates to true.

Brackets

Use brackets to either remove ambiguity or group expressions to improve readability. For example, consider following expression:

trueIdentity or trueIdentity and falseIdentity

What does above expression evaluates to? If or executes first, this will result in false. Otherwise in true. To remove this ambiguity you can be explicit by grouping sub-expressions using brackets as follows.Hence following observations.

trueIdentity or (trueIdentity and falseIdentity) == trueIdentity

(trueIdentity or trueIdentity) and falseIdentity == falseIdentity

Use Brackets as follows.

val rule1= falseIdentity and trueIdentity and trueIdentity

val rule2= trueIdentity and trueIdentity and trueIdentity

val rule3=rule1 and rule2

val rule4=rule3 or trueIdentity

val rule5=rule4 and not(falseIdentity)

(all(rule5,trueIdentity) and falseIdentity) or trueIdentity

The above expression evaluates to true.

Any Operator

Keywords: any

The any operator takes a list of behaviours and evaluates to true if any one of the behaviours evaluate to true.

any(falseIdentity) == falseIdentity

any(falseIdentity,falseIdentity) == falseIdentity

any(trueIdentity) == trueIdentity

any(trueIdentity,trueIdentity) == trueIdentity

any(trueIdentity,falseIdentity) == trueIdentity

any(trueIdentity,........) == trueIdentity

Use the any operator as follows:

val rule1= falseIdentity and trueIdentity and trueIdentity

val rule2= trueIdentity and trueIdentity and trueIdentity

val rule3=rule1 and rule2

val rule4=rule3 or trueIdentity

val rule5=rule4 and not(falseIdentity)

val rule6=(all(rule5,trueIdentity) and falseIdentity) or trueIdentity

any(rule6,falseIdentity,falseIdentity)

The above expression evaluates to true.

Given-Choose-Otherwise Operation

Keywords: given,choose,otherwise

Given-Choose-Otherwise works like if conditions in languages like Java and Scala. If given behaviour evaluates to true, behaviour specified for choose is evaluated as a result else behaviour specified for otherwise is evaluated as a result( or falseIdentity if otherwise clause is missing)

given(falseIdentity) choose falseIdentity == falseIdentity

given(falseIdentity) choose trueIdentity == falseIdentity

given(trueIdentity) choose falseIdentity == falseIdentity

given(trueIdentity) choose trueIdentity == trueIdentity

given(falseIdentity) choose falseIdentity otherwise trueIdentity == trueIdentity

given(falseIdentity) choose falseIdentity otherwise falseIdentity == falseIdentity

given(falseIdentity) choose trueIdentity otherwise trueIdentity == trueIdentity

given(falseIdentity) choose trueIdentity otherwise falseIdentity == falseIdentity

given(trueIdentity) choose falseIdentity otherwise falseIdentity == falseIdentity

given(trueIdentity) choose falseIdentity otherwise trueIdentity == falseIdentity

given(trueIdentity) choose trueIdentity otherwise falseIdentity == trueIdentity

given(trueIdentity) choose trueIdentity otherwise trueIdentity == trueIdentity

Use given, choose, otherwise operator as follows.

val rule1= falseIdentity and trueIdentity and trueIdentity

val rule2= trueIdentity and trueIdentity and trueIdentity

val rule3=rule1 and rule2

val rule4=rule3 or trueIdentity

val rule5=rule4 and not(falseIdentity)

val rule6=(all(rule5,trueIdentity) and falseIdentity) or trueIdentity

val rule7=any(rule6,falseIdentity,falseIdentity)

given(rule7) choose falseIdentity otherwise trueIdentity

The above expression evaluates to false.