Mode Checking

[eignnx]

Impl mode inference and checking.

Maybe add [Det] relation which assets that it's goal argument is deterministic?

[eignnx]

Base cases:

[true] :: det
[false] :: fail
[MustBeInt] :: semi

[list in][member out] :: multi
[list in][member in] :: semi
[list out][member out] :: multi
[list out][member in] :: semi

[prefix in][suffix in][compound out] :: det
[prefix out][suffix out][compound _] :: multi
[prefix in][suffix in][compound in] :: semi
[prefix out][suffix in][compound out] :: multi
[prefix in][suffix out][compound out] :: multi
[prefix out][suffix in][compound in] :: multi

[file_path in][clauses out][directives out] :: det (throws error if problem)