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Various decisions

The syntax of a PL has many low-level details. The current decision taken are:

  • use () for function call
  • use [ ] for declaring structural things and DSL declarations
  • use { } for declaring executable things
  • use {[ ]} for declaring executable things in DSL syntax
  • same prefix keyword like “slot” has different meaning if it is used inside () or [] or {}: inside [ ] it declares a slot, inside .( ) it assign the slot value to cloned value.
  • T is not allowed, only ../T or some explicit Type/.../T
  • slot ~::Color means slot color::Color and it is used when the slot name has the same name of the type. In the type there can be also parameters instantiation
  • in nested { }, “self” is still the current object of the method
  • methods starting with _ are private
  • : is used for meta-info/annotations involving the parent scope
  • :^ is used for meta-info involving the previous code

Compact notation for lists

var x* Int*[ 10, 20, 30]
:^# the type of `x*` is inferred, and the init expression uses the `Int*` DSL syntax for declaring it

Special names clashes

Inside a lambda like self.filter({~.isa(../Var)}) the ~ is related to ~this that is the unique lambda term. In case of conflict with a parent ~ representing another lamda term, or a parent visit something { ... }, then it is mandatory to use ~this for the lambda term.

Dok statements starts always with a prefix

Dok syntax follow a uniform pattern:

  • instruction type (e.g. fun, var, slot, data, set)
  • identifier name
  • params inside parens
  • etc…


Sigils are used for

  • * for a stream of values
  • + for a stream of values with at least one value
  • ! for a method changing the slots of an object, and that it is backtrable if in Dok, or not dangerous if in a DSL. It returns by default the new version of self
  • !! for non-backtrable operations, changing the state of the system and returning a result
  • ? for a predicate returning true or false
  • $ for a mutable reference, i.e. it is not a value