Instruct (acutis.Acutis_internals.Instruct)

To evaluate a Compile.t, we define an abstract language in "tagless final" style by using a module type. Each language construct is defined as an OCaml function so we automatically inherit the full type safety of any OCaml program.

We can evaluate the language in multiple ways. For example we can interpret it as an OCaml program, we can pretty-print it, or we can output it in a concrete language like JavaScript (which is just another form of pretty-printing). We can also add modular optimizations.

Our abstract language is roughly based on JavaScript. It has expressions, statements, loops, let-bindings, mutable references, hash tables, first-class functions, and asynchronous monads (i.e. promises).

module type SEM = sig ... end

Define the semantics of our abstract language.

module Make (I : SEM) : sig ... end

Create evaluation instructions for a given language implementation.

module type TRANS = sig ... end

To transform the language's output, such as for an optimization, we need to define a module that can translate terms "forward" to the transformed state and "backward" to the original representation.

module MakeTrans
  (T : TRANS)
  (F : SEM with type 'a exp = 'a T.from_exp and type 'a stmt = 'a T.from_stmt) : 
  SEM
    with type 'a stmt = 'a T.stmt
     and type 'a obs = 'a F.obs
     and type 'a exp = 'a T.exp
     and type 'a ref = 'a F.ref
     and type 'a hashtbl = 'a F.hashtbl
     and type buffer = F.buffer
     and type 'a promise = 'a F.promise
     and type 'a External.linear = 'a F.External.linear
     and type 'a External.assoc = 'a F.External.assoc
     and type External.t = F.External.t
     and type 'a External.classify = 'a F.External.classify
     and type Data.t = F.Data.t
     and type import = F.import

Apply a transformation module and a semantics module to produce a new semantics module that uses the transformation state.

val pp : 
  (Stdlib__Format.formatter -> 'a -> unit) ->
  Stdlib__Format.formatter ->
  'a0 Compile.t ->
  unit

Pretty-print the instructions for a compiled template.