Syntax improvements and additions

[mitchphillipson]

Endowments

In MPSGE there is syntax of the form

e: E   q:Q    r:RATE

This is equivalent to

e: E    q:Q*RATE

We should add a keyword to the endowment constructor of the form

@endowment(E, Q, ration= RATE)

This is the same as #100

Taxes

It's possible in a netput to have something of the form

I:X    q:Q    A:CONS    N:Z     M:C

This is equivalent to

I:X    q:Q    A:CONS    t:Z*C

N stands for endogenous and M for multplier

Productivity Externality

Currently in MPSGE we must do

i:P   Q: L*x    P: 1/L

It would be preferable to have syntax of the form

i:P   Q: x   X: L

[EliLazarus]

I'm generally in favour of more articulation and flexibility, so e.g. I'd rather have e: E q:Q*RATE than either e: E q:Q r:RATE or @endowment(E, Q, ration= RATE) I think it's clearer to read, and interpret, and allows other operations. There's some economics in there (MPSGE/GAMS construction) that suggests those particular combinations, but I don't think it's necessary to lock those in. Better to provide documentation on the economic intuition of those, but leave open other possibilities for users to construct.

We can discuss.

[EliLazarus]

Adding a reference back to #100 to make sure we have that clearly in mind for all this.