I know you mentioned we could just rename the JS AST @paf31, but I couldn't resist having a look to see if we could do something a bit more "core"/reusable for other targets. At the moment I have this:

data Expr a
  -- |
  -- A literal value (`Literal` is reused from `CoreFn` here).
  --
  = Literal a (Literal (Expr a))
  -- |
  -- An object property or array accessor expression (prop/index, obj/array)
  --
  | Accessor a (Expr a) (Expr a)
  -- |
  -- An anonymous function value (arguments, body)
  --
  | AnonFunction a [Ident] [Statement a]
  -- |
  -- Function application
  --
  | App a (Expr a) [Expr a]
  -- |
  -- Variable reference
  --
  | Var a Ident

type Label = String

data Statement a
  -- |
  -- An expression whose value is discarded (probably causes a side effect)
  --
  = Expr (Expr a)
  -- |
  -- A function introduction (name, arguments, body)
  --
  | Function Ident [Ident] [Statement a]
  -- |
  -- A variable introduction and optional initialization
  --
  | VarIntroduction Ident (Maybe (Expr a))
  -- |
  -- A variable assignment (assignee, value)
  --
  | Assignment (Expr a) (Expr a)
  -- |
  -- While-style loop (condition, body)
  --
  | Loop (Expr a) [LoopStatement a]
  -- |
  -- A loop over an object's keys (key variable, object value, body)
  --
  | ObjectIterator Ident (Expr a) [LoopStatement a]
  -- |
  -- If-then-else statement
  --
  | IfElse (Expr a) [Statement a] (Maybe [Statement a])
  -- |
  -- Return statement
  --
  | Return (Expr a)
  -- |
  -- Throw statement
  --
  | Throw (Expr a)
  -- |
  -- InstanceOf test
  --
  | InstanceOf (Expr a) (Expr a)
  -- |
  -- Labelled statement
  --
  | Label Label (Statement a)
  -- |
  -- Commented statement
  --
  | Comment [Comment] (Statement a)

data LoopStatement a
  -- |
  -- Break statement
  --
  = Break (Maybe Label)
  -- |
  -- Continue statement
  --
  | Continue (Maybe Label)
  -- |
  -- Standard statement
  --
  | Statement (Statement a)

I don't know if this is the kind of route we do want to go down, but figured I'd throw it out there. It's not really expression orientated as @jdegoes suggested, but it feels like a middle ground between being too JS specific and something completely different.

The only thing in here I'm definitely unhappy with is InstanceOf, as we don't have a representation of classes at all in this, but if we want to desugar cases into IfElses then we need something like InstanceOf, but perhaps it just needs to be more PureScript specific, like IsDataConstructor Ident (Expr a) or something?

Also would we want annotations on Statement as well as Expr?

Anyway, thoughts please.

Uh oh!

Refactor imperative core AST #711

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