dok/syntax

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

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