Scala DSL: method chaining with parameterless methods

Question

i am creating a small scala DSL and running into the following problem to which i dont really have a solution. A small conceptual example of what i want to achieve:

(Compute
 write "hello"
 read 'name
 calc()
 calc()
 write "hello" + 'name
)

the code defining this dsl is roughly this:

Object Compute extends Compute{
  ...
 implicit def str2Message:Message = ...
}
class Compute{
 def write(msg:Message):Compute = ...
 def read(s:Symbol):Compute = ...
 def calc():Compute = { ... }
}

Now the question: how can i get rid of these parenthesis after calc? is it possible? if so, how? just omitting them in the definition does not help because of compilation errors.

Answer 1

ok, i think, i found an acceptable solution... i now achieved this possible syntax

 | write "hello"
 | read 'name
 | calc
 | calc
 | write "hello " + 'name 

using an object named "|", i am able to write nearly the dsl i wanted. normaly, a ";" is needed after calc if its parameterless. The trick here is to accept the DSL-object itself (here, its the "|" on the next line). making this parameter implicit also allows calc as a last statement in this code. well, looks like it is definitly not possible to have it the way i want, but this is ok too

Answer 2

It's not possible to get rid of the parenthesis, but you can replace it. For example:

object it

class Compute {
 def calc(x: it.type):Compute = { ... }

(Compute
 write "hello"
 read 'name
 calc it
 calc it
 write "hello" + 'name
)

To expand a bit, whenever Scala sees something like this:

object method
non-reserved-word

It assumes it means object.method(non-reserved-word). Conversely, whenever it sees something like this:

object method object
method2 object2

It assumes these are two independent statements, as in object.method(object); method2.object, expecting method2 to be a new object, and object2 a method.

These assumptions are part of Scala grammar: it is meant to be this way on purpose.