9 Deep-guard Concurrent Constraint Combinators: Combinator

This chapter describes deep-guard concurrent constraint combinators such as conditional and disjunction. Most combinators implemented by the module Combinator are available by convenient syntax and are described in Chapter 12 of “Tutorial of Oz”.

'not'

{Combinator.'not' +P}

implements deep-negation where the nullary procedure P gives the statement to negate.

Is supported by special syntax. The statement

not S end

expands to

{Combinator.'not' proc {$} S end}

'reify'

{Combinator.'reify' +P $D}

implements deep-reification where the nullary procedure P gives the statement to reify.

'cond'

{Combinator.'cond' +T +P}

implements parallel concurrent conditional.

'or'

{Combinator.'or' +T}

implements disjunction. T is a tuple of either nullary or unary procedures. The special syntax statement

      or S1 
      [] S2 
      [] S3 then S4 
      end 
      

corresponds to the following

    local 
       proc {C1} S1 end 
       proc {C2} S2 end 
       fun {C3} S3 proc {$} S4 end end 
    in 
       {Combinator.'or' C1#C2#C3}
    end 
   

'choice'

{Combinator.'choice' +T}

implements choice point construction.

'dis'

{Combinator.'dis' +T}

implements andorra-style disjunction.