Placeholders and Function Calls

[stasm]

At the yesterday's plenary meeting I presented a proposal for a middle-ground data model for placeholders and function calls. I invite everyone to comment on the slides and to share feedback here. Please structure your feedback as separate comments to allow for more discussion in the comment's replies.

The proposed data model is a compromise between the EM and the EZ model. In particular I propose that:

• we refactor the data model of placeholders in the EM model and introduce explicit variable references — this brings it closer to the EZ and allows one-level-deep indirection via FUNC($var),
• we drop nested function calls from the EZ model — and recommend that the complexity should instead be handled by programmers inside custom functions' implementation.

interface FunctionCall {
	name: string;
	args: Array<Argument>;
	opts: Record<string, Parameter>;
}

type Argument = VariableReference | StringLiteral;
type Parameter = VariableReference | StringLiteral | BooleanLiteral | NumberLiteral;

interface Variant {
	keys: Array<StringLiteral>;
	value: Array<Part>;
}

type Part = StringLiteral | VariableReference | FunctionCall;

I implemented this proposal in /experiments/stasm/third. This prototype explores a few orthogonal ideas too (e.g. #149), but let's discuss them elsewhere and keep this thread on-topic.