Module `Sexp_macro__.Macro`

This module implements a limited form of evaluation within s-expressions, usually called macro expansion. The follow macros are supported:

(:include filename) expands to the list of s-expressions contained in filename, as if the contents of filename were directly inserted in place of (:include filename). A relative filename is taken with respect to the file that contains the include macro.
(:let v (v1 ... vn) S1 ... Sm) defines a macro-variable v with labelled parameters v1, ..., vn and body S1 ... Sm. The definition itself expands to nothing. All macro-variables (v and v1 .. vn here) are lexically scoped. An error is reported if S1 ... Sm is empty. .
(:use v (v1 SS1) ... (vn SSn)) calls the macro-variable v with the expansions of SS1 .. SSn, i.e. expands to the body of v and substitutes SS1 .. SSn for the parameters v1, ..., vn of v. Parameters take no arguments. An error is reported if v is not in scope, or the parameter labels do not match.
(:concat S1 ... Sn) expands S1 ... Sn, and assuming the expansions are all atoms, expands to a single atom of their concatenation. An error is reported otherwise.

Macros other than :include will be called 'local'. All :include macros are expanded before all local macros, so (:include (:use x)) is always an error and if file1 includes file2 and file2 include file3, file1 can use templates defined in file3. However files can only use macro-variables that they brought in scope: if file1 defines a macro-variable a and includes file2, file2 cannot use a.

Example -------

Assume that input.sexp contains

   (:include defs.sexp)
   (:include template.sexp)
   (:use f (a (:use a)) (b (:use b)))

the file defs.sexp contains

   (:let a () hello)
   (:let b () " world")

and the file template.sexp contains

   (:let f (a b) (:concat (:use a) (:use b)))

Then load_sexp "input.sexp" will return "hello world".

type 'a conv = [ | `Result of 'a | `Error of exn * Sexplib.Sexp.t ]

val sexp_of_conv : ('a -> Sexplib.Sexp.t) -> 'a conv -> Sexplib.Sexp.t

type 'a annot_conv = [ `Result of 'a | `Error of exn * Sexplib.Sexp.Annotated.t ] as 'body constraint 'body = 'a Sexplib.Sexp.Annotated.conv

val sexp_of_annot_conv : ('a -> Sexplib.Sexp.t) -> 'a annot_conv -> Sexplib.Sexp.t
val expand_local_macros : Sexplib.Sexp.t list -> Sexplib.Sexp.t list conv: expand_local_macros sexps takes a list of sexps and performs macro-expansion on them, except that an error will be returned if an :include macro is found.

module type Sexp_loader = sig ... end: A version of load_sexps that is functorized with respect to the functions that load the sexps from files and the corresponding monad.

module Loader : functor (S : Sexp_loader) -> sig ... end

val add_error_location : string -> exn -> exn