Multiple modules

[brendanzab]

It would be nice to support breaking up fathom files into multiple modules, especially as files like opentype.fathom get larger.

I’d imagine imports could go at the top of a file:

module opentype;

import fathom.{ u32be, ... etc ... };

import opentype.common.{ unknown_table, optional_table };
import opentype.tables;

And later:

            cvt <- optional_table "cvt " tables.cvt,
            fpgm <- optional_table "fpgm" unknown_table,

Imports should be qualified by default, and form a DAG.

Some questions:

• what import syntax should we use?
• how do we find new modules relative to an existing module?
• how do we dump multiple modules for snapshot testing?
• how doe we represent modules in the elaborator/evaluator(s)/etc.

[Kmeakin]

What about local imports?
local import fathom.u32be; foo would function like let.

Alternatively, we could have an expression version of import, which would be more orthogonal and not requre another binder form in the core syntax
let {u32be} = import fathom; foo