module/component/function/record as a types

[amitu]

We have module as a type syntax.

-- import: some-module
-- component foo:
module m: some-module

... definition omitted ... 
-- end: foo

And caller:

-- import: a-module

-- foo:
m: a-module

The module a-module must have the same "type" as some-module, meaning all definitions in some-module x must also be present in a-module with same/compatible type.

We can do the same for component as type:

-- component bar:
component foo: foo
function f: some-fn

-- end: bar

-- component foo:
-- end: foo

-- void some-fn():
.. omitted ..

And caller of bar needs to provide a component with signature compatible with foo,. and function with signature compatible with some-fn.

Record Typ

Record types can be considered traits.

-- component f:
record x: person

-- end: f

-- record person:
string name:
integer age:

Caller of f must provide a record that is compatible with person. When looking at compatibility, we check if all the methods/functions defined on person are present with same signature on the provided type.

Also the fields of the record must either be present in the provided record with same type, or a getting/setter with appropriate name must be present on the provided record, and will be called transparently.