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_build/
/setup.data
/setup.log
/*.exe
/*.docdir
/*.native
/*.byte

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THIS SOFTWARE IS PROVIDED BY INRIA AND CONTRIBUTORS "AS IS" AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INRIA OR ITS CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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To apply the Apache License to your work, attach the following
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version = "$(pkg_version)"
description = "Monadic let-bindings"
requires = "ppx_core ppx_driver"
archive(ppx_driver, byte ) = "ppx_let.cma"
archive(ppx_driver, native ) = "ppx_let.cmxa"
archive(ppx_driver, native, plugin) = "ppx_let.cmxs"
exists_if = "ppx_let.cma"
ppx(-ppx_driver) = "./ppx"

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# Generic Makefile for oasis project
SETUP := setup.exe
NAME := ppx_let
PREFIX = $(shell grep ^prefix= setup.data | cut -d\" -f 2)
# Default rule
default: build
setup.exe: _oasis setup.ml
ocamlfind ocamlopt -o $@ -linkpkg -package ocamlbuild,oasis.dynrun setup.ml || \
ocamlfind ocamlc -o $@ -linkpkg -package ocamlbuild,oasis.dynrun setup.ml || true
for f in setup.*; do [ $$f = $@ -o $$f = setup.ml ] || rm -f $$f; done
build: $(SETUP) setup.data
./$(SETUP) -build $(BUILDFLAGS)
$(MAKE) $(NAME).install
doc: $(SETUP) setup.data build
./$(SETUP) -doc $(DOCFLAGS)
test: $(SETUP) setup.data build
./$(SETUP) -test $(TESTFLAGS)
all: $(SETUP)
./$(SETUP) -all $(ALLFLAGS)
$(MAKE) $(NAME).install
$(NAME).install: js-utils/gen_install.ml setup.log setup.data
ocaml -I js-utils js-utils/gen_install.ml
install: $(NAME).install
opam-installer -i --prefix $(PREFIX) $(NAME).install
uninstall: $(NAME).install
opam-installer -u --prefix $(PREFIX) $(NAME).install
reinstall: $(NAME).install
opam-installer -u --prefix $(PREFIX) $(NAME).install &> /dev/null || true
opam-installer -i --prefix $(PREFIX) $(NAME).install
bin.tar.gz: $(NAME).install
rm -rf _install
mkdir _install
opam-installer -i --prefix _install $(NAME).install
tar czf bin.tar.gz -C _install .
rm -rf _install
bin.lzo: $(NAME).install
rm -rf _install
mkdir _install
opam-installer -i --prefix _install $(NAME).install
cd _install && lzop -1 -P -o ../bin.lzo `find . -type f`
rm -rf _install
clean: $(SETUP)
./$(SETUP) -clean $(CLEANFLAGS)
distclean: $(SETUP)
./$(SETUP) -distclean $(DISTCLEANFLAGS)
configure: $(SETUP)
./$(SETUP) -configure $(CONFIGUREFLAGS)
setup.data: $(SETUP)
./$(SETUP) -configure $(CONFIGUREFLAGS)
.PHONY: default build doc test all install uninstall reinstall clean distclean configure

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A ppx rewriter for monadic and applicative let bindings and match statements.
Overview
--------
The aim of this rewriter is to make monadic and applicative code look
nicer by writing custom binders the same way that we normally bind
variables. In OCaml, the common way to bind the result of a
computation to a variable is:
```ocaml
let VAR = EXPR in BODY
```
ppx\_let simply adds two new binders: `let%bind` and
`let%map`. These are rewritten into calls to the `bind` and
`map` functions respectively. These functions are expected to have
```ocaml
val map : 'a t -> f:('a -> 'b) -> 'b t
val bind : 'a t -> ('a -> 'b t) -> 'b t
```
for some type `t`, as one might expect.
These functions are to be provided by the user, and are generally
expected to be part of the signatures of monads and applicatives
modules. This is the case for all monads and applicatives defined by
the Jane Street's Core suite of libraries. (see the section below on
getting the right names into scope).
### Parallel bindings
ppx\_monad understands parallel bindings as well. i.e.:
```ocaml
let%bind VAR1 = EXPR1 and VAR2 = EXPR2 and VAR3 = EXPR3 in BODY
```
The `and` keyword is seen as a binding combination operator. To do so
it expects the presence of a `both` function, that lifts the OCaml
pair operation to the type `t` in question:
```ocaml
val both : 'a t -> 'b t -> ('a * 'b) t
```
### Match statements
We found that this form was quite useful for match statements as
well. So for convenience ppx\_monad also accept `%bind` and `%map` on
the `match` keyword. Morally `match%bind expr with cases` is seen as
`let%bind x = expr in match x with cases`.
Syntactic forms and actual rewriting
------------------------------------
`ppx_let` adds four syntactic forms
```ocaml
let%bind P = M in E
let%map P = M in E
match%bind M with P1 -> E1 | P2 -> E2 | ...
match%map M with P1 -> E1 | P2 -> E2 | ...
```
that expand into
```ocaml
bind M (fun P -> E)
map M (fun P -> E)
bind M (function P1 -> E1 | P2 -> E2 | ...)
map M (function P1 -> E1 | P2 -> E2 | ...)
```
respectively.
As with `let`, `let%bind` and `let%map` also support multiple
*parallel* bindings via the `and` keyword:
```ocaml
let%bind P1 = M1 and P2 = M2 and P3 = M3 and P4 = M4 in E
let%map P1 = M1 and P2 = M2 and P3 = M3 and P4 = M4 in E
```
that expand into
```ocaml
let x1 = M1 and x2 = M2 and x3 = M3 and x4 = M4 in
bind
(both x1 (both x2 (both x3 x4)))
(fun (P1, (P2, (P3, P4))) -> E)
let x1 = M1 and x2 = M2 and x3 = M3 and x4 = M4 in
map
(both x1 (both x2 (both x3 x4)))
(fun (P1, (P2, (P3, P4))) -> E)
```
respectively. (Instead of `x1`, `x2`, ... ppx\_monad uses
variable names that are unlikely to clash with other names)
As with `let`, names introduced by left-hand sides of the let bindings
are not available in subsequent right-hand sides of the same sequence.
Getting the right names in scope
--------------------------------
The description of how the `%bind` and `%map` syntax extensions expand
left out the fact that the names `bind`, `map`, `both`, and `return`
are not used directly, but rather qualified by `Let_syntax`. For
example, we use `Let_syntax.bind` rather than merely `bind`. This
means one just needs to get a properly loaded `Let_syntax` module in
scope to use `%bind` and `%map`.
For monads, `Core.Std.Monad.Make` produces a submodule `Let_syntax` of
the appropriate form.
For applicatives. The convention for these modules is to have a
submodule `Let_syntax` of the form
```ocaml
module Let_syntax : sig
val return : 'a -> 'a t
val map : 'a t -> f:('a -> 'b) -> 'b t
val both : 'a t -> 'b t -> ('a * 'b) t
module Open_on_rhs : << some signature >>
module Open_in_body : << some signature >>
end
```
The `Open_on_rhs` and `Open_in_body` submodules are used by variants
of `%map` and `%bind` called `%map_open` and `%bind_open`.
The `Open_on_rhs` submodule is locally opened on the right hand sides
of the rewritten let bindings in `%map_open` and `%bind_open`
expressions. This is useful when programming with applicatives, which
operate in a staged manner where the operators used to construct the
applicatives are distinct from the operators used to manipulate the
values those applicatives produce. For monads, `Open_on_rhs` contains
`return`.
The `Open_in_body` submodule is locally opened in the body of either a
`let%map_open` or `let%bind_open`. It is often empty for
applicatives. For monads in `Core`, it contains `return`.
For `match%map_open` and `match%bind_open` expressions, `Open_on_rhs`
is opened for the expression being matched on, and `Open_in_body` is
opened in the body of each pattern match clause.

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The repository contains 3rd-party code in the following locations and
under the following licenses:
- type_conv, sexplib and bin_prot: based on Tywith, by Martin
Sandin. License can be found in base/sexplib/LICENSE-Tywith.txt,
base/type_conv/LICENSE-Tywith.txt, and base/bin_prot/LICENSE-Tywith.txt.
- Core's implementation of union-find: based on an implementation by
Henry Matthew Fluet, Suresh Jagannathan, and Stephen Weeks. License
can be found in base/core/MLton-license.
- Various Core libraries are based on INRIA's OCaml
distribution. Relicensed under Apache 2.0, as permitted under the
Caml License for Consortium members:
http://caml.inria.fr/consortium/license.en.html
See also the disclaimer INRIA-DISCLAIMER.txt.

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OASISFormat: 0.4
OCamlVersion: >= 4.02.3
FindlibVersion: >= 1.3.2
Name: ppx_let
Version: 113.24.00
Synopsis: Monadic let-bindings
Authors: Jane Street Group, LLC <opensource@janestreet.com>
Copyrights: (C) 2015-2016 Jane Street Group LLC <opensource@janestreet.com>
Maintainers: Jane Street Group, LLC <opensource@janestreet.com>
License: Apache-2.0
LicenseFile: LICENSE.txt
Homepage: https://github.com/janestreet/ppx_let
Plugins: StdFiles (0.3), DevFiles (0.3), META (0.3)
XStdFilesAUTHORS: false
XStdFilesREADME: false
BuildTools: ocamlbuild
FilesAB: META.ab
Description:
Part of the Jane Street's PPX rewriters collection.
Library ppx_let
Path: src
Pack: false
Modules: Ppx_let
BuildDepends: ppx_core,
ppx_driver
Executable ppx
Path: as_ppx
MainIs: ppx.ml
CompiledObject: best
BuildDepends: ppx_let,
ppx_driver

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<**/*.ml{,i}>: warn(-40), no_alias_deps
<**/*>: thread
# This prevents the implicit addition of -ppx options by ocamlfind
<**/*.ml{,i}>: predicate(ppx_driver)
<as_ppx/ppx.{byte,native}>: predicate(ppx_driver)
<src/*>: linkall
# OASIS_START
# OASIS_STOP

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Ppx_driver.run_as_ppx_rewriter ()

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#!/bin/sh
# OASIS_START
make configure CONFIGUREFLAGS="$*"
# OASIS_STOP

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Monadic let-bindings
Part of the Jane Street's PPX rewriters collection.

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(* Generate <package>.install from setup.log *)
#use "install_tags.ml"
module String_map = Map.Make(String)
let string_map_of_list =
List.fold_left
(fun acc (k, v) ->
assert (not (String_map.mem k acc));
String_map.add k v acc)
String_map.empty
let lines_of_file fn =
let ic = open_in fn in
let rec loop acc =
match input_line ic with
| exception End_of_file ->
close_in ic;
List.rev acc
| line ->
loop (line :: acc)
in
loop []
let read_setup_log () =
lines_of_file "setup.log"
|> List.map (fun line -> Scanf.sscanf line "%S %S" (fun tag arg -> (tag, arg)))
let read_setup_data () =
lines_of_file "setup.data"
|> List.map (fun line -> Scanf.sscanf line "%[^=]=%S" (fun k v -> (k, v)))
let remove_cwd =
let prefix = Sys.getcwd () ^ "/" in
let len_prefix = String.length prefix in
fun fn ->
let len = String.length fn in
if len >= len_prefix && String.sub fn 0 len_prefix = prefix then
String.sub fn len_prefix (len - len_prefix)
else
fn
let gen_section oc name files =
let pr fmt = Printf.fprintf oc (fmt ^^ "\n") in
pr "%s: [" name;
List.iter
(fun (src, dst) ->
let src = remove_cwd src in
let dst =
match dst with
| None -> Filename.basename src
| Some fn -> fn
in
if src = dst then
pr " %S" src
else
pr " %S {%S}" src dst)
files;
pr "]"
let rec filter_log tags log acc =
match log with
| [] -> acc
| (tag, fname) :: rest ->
match String_map.find tag tags with
| exception Not_found -> filter_log tags rest acc
| dst -> filter_log tags rest ((fname, dst) :: acc)
let () =
let log = read_setup_log () in
let setup_data = read_setup_data () in
let ext_dll =
match List.assoc "ext_dll" setup_data with
| ext -> ext
| exception Not_found -> ".so"
in
let merge name files map =
match String_map.find name map with
| files' -> String_map.add name (files @ files') map
| exception Not_found -> String_map.add name files map
in
let sections =
List.fold_left
(fun acc (name, tags, extra_files) ->
let tags = string_map_of_list tags in
let files = filter_log tags log [] @ extra_files in
if name = "lib" then
let stubs, others =
List.partition
(fun (fn, _) -> Filename.check_suffix fn ext_dll)
files
in
merge "lib" others (merge "stublibs" stubs acc)
else
merge name files acc)
String_map.empty sections
|> String_map.bindings
|> List.filter (fun (_, l) -> l <> [])
in
let oc = open_out (package_name ^ ".install") in
List.iter (fun (name, files) -> gen_section oc name files) sections;
close_out oc

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let package_name = "ppx_let"
let sections =
[ ("lib",
[ ("built_lib_ppx_let", None)
],
[ ("META", None)
])
; ("libexec",
[ ("built_exec_ppx", Some "ppx")
],
[])
]

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(* OASIS_START *)
(* OASIS_STOP *)
# 3 "myocamlbuild.ml"
(* Temporary hacks *)
let js_hacks = function
| After_rules ->
rule "Generate a cmxs from a cmxa"
~dep:"%.cmxa"
~prod:"%.cmxs"
~insert:`top
(fun env _ ->
Cmd (S [ !Options.ocamlopt
; A "-shared"
; A "-linkall"
; A "-I"; A (Pathname.dirname (env "%"))
; A (env "%.cmxa")
; A "-o"
; A (env "%.cmxs")
]));
(* Pass -predicates to ocamldep *)
pflag ["ocaml"; "ocamldep"] "predicate" (fun s -> S [A "-predicates"; A s])
| _ -> ()
let () =
Ocamlbuild_plugin.dispatch (fun hook ->
js_hacks hook;
dispatch_default hook)

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opam-version: "1.2"
maintainer: "opensource@janestreet.com"
authors: ["Jane Street Group, LLC <opensource@janestreet.com>"]
homepage: "https://github.com/janestreet/ppx_let"
bug-reports: "https://github.com/janestreet/ppx_let/issues"
dev-repo: "https://github.com/janestreet/ppx_let.git"
license: "Apache-2.0"
build: [
["./configure" "--prefix" prefix]
[make]
]
depends: [
"ocamlbuild" {build}
"oasis" {build & >= "0.4"}
"ocamlfind" {build & >= "1.3.2"}
"ppx_core"
"ppx_driver"
]
available: [ ocaml-version >= "4.02.3" ]

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(* OASIS_START *)
open OASISDynRun;;
open OASISTypes;;
(* OASIS_STOP *)
let () = setup ()

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open! StdLabels
open Ppx_core.Std
open Parsetree
open Ast_builder.Default
module List = struct
include List
let reduce_exn l ~f =
match l with
| [] -> invalid_arg "List.reduce_exn"
| hd :: tl -> fold_left tl ~init:hd ~f
end
module Extension_name = struct
type t =
| Bind
| Bind_open
| Map
| Map_open
let operator_name = function
| Bind | Bind_open -> "bind"
| Map | Map_open -> "map"
let to_string = function
| Bind -> "bind"
| Bind_open -> "bind_open"
| Map -> "map"
| Map_open -> "map_open"
end
let let_syntax = "Let_syntax"
let open_on_rhs ~loc = Located.mk ~loc (Longident.Ldot (Lident let_syntax, "Open_on_rhs" ))
let open_in_body ~loc = Located.mk ~loc (Longident.Ldot (Lident let_syntax, "Open_in_body"))
let eoperator ~loc func =
let lid : Longident.t = Ldot (Longident.Lident let_syntax, func) in
pexp_ident ~loc (Located.mk ~loc lid)
;;
let expand_with_tmp_vars ~loc bindings expr ~f =
match bindings with
| [_] -> f ~loc bindings expr
| _ ->
let tmp_vars = List.map bindings ~f:(fun _ -> gen_symbol ~prefix:"__let_syntax" ()) in
let s_rhs_tmp_var (* s/rhs/tmp_var *) =
List.map2 bindings tmp_vars ~f:(fun vb var ->
{ vb with pvb_expr = evar ~loc:vb.pvb_expr.pexp_loc var })
in
let s_lhs_tmp_var (* s/lhs/tmp_var *) =
List.map2 bindings tmp_vars ~f:(fun vb var ->
{ vb with pvb_pat = pvar ~loc:vb.pvb_pat.ppat_loc var })
in
pexp_let ~loc Nonrecursive s_lhs_tmp_var (f ~loc s_rhs_tmp_var expr)
;;
let bind_apply ~loc extension_name ~arg ~fn =
let fn_label =
match (extension_name : Extension_name.t) with
| Bind | Bind_open -> ""
| Map | Map_open -> "f"
in
pexp_apply ~loc
(eoperator ~loc (Extension_name.operator_name extension_name))
[("", arg); (fn_label, fn)]
;;
let maybe_open extension_name ~loc ~to_open:module_to_open expr =
match (extension_name : Extension_name.t) with
| Bind | Map -> expr
| Bind_open | Map_open -> pexp_open ~loc Override (module_to_open ~loc) expr
;;
let expand_let extension_name ~loc bindings body =
(* Build expression [both E1 (both E2 (both ...))] *)
let nested_boths =
let rev_boths = List.rev_map bindings ~f:(fun vb -> vb.pvb_expr) in
List.reduce_exn rev_boths ~f:(fun acc e ->
let loc = e.pexp_loc in
eapply ~loc (eoperator ~loc "both") [e; acc])
in
(* Build pattern [(P1, (P2, ...))] *)
let nested_patterns =
let rev_patts = List.rev_map bindings ~f:(fun vb -> vb.pvb_pat) in
List.reduce_exn rev_patts ~f:(fun acc p ->
let loc = p.ppat_loc in
ppat_tuple ~loc [p; acc])
in
bind_apply ~loc extension_name ~arg:nested_boths
~fn:(pexp_fun ~loc "" None nested_patterns
(maybe_open extension_name ~loc ~to_open:open_in_body body))
;;
let expand_match extension_name ~loc expr cases =
let cases =
List.map cases ~f:(fun case ->
{ case with
pc_rhs = maybe_open extension_name ~loc ~to_open:open_in_body case.pc_rhs;
})
in
bind_apply ~loc extension_name
~arg:(maybe_open extension_name ~loc ~to_open:open_on_rhs expr)
~fn:(pexp_function ~loc cases)
;;
let expand ~loc:_ ~path:_ extension_name expr =
let loc = expr.pexp_loc in
let expansion =
match expr.pexp_desc with
| Pexp_let (Nonrecursive, bindings, expr) ->
let bindings =
List.map bindings ~f:(fun vb ->
{ vb with
pvb_expr = maybe_open extension_name ~loc ~to_open:open_on_rhs vb.pvb_expr;
})
in
expand_with_tmp_vars ~loc bindings expr ~f:(expand_let extension_name)
| Pexp_let (Recursive, _, _) ->
Location.raise_errorf ~loc "'let%%%s' may not be recursive"
(Extension_name.to_string extension_name)
| Pexp_match (expr, cases) ->
expand_match extension_name ~loc expr cases
| _ ->
Location.raise_errorf ~loc
"'%%%s' can only be used with 'let' and 'match'"
(Extension_name.to_string extension_name)
in
{ expansion with pexp_attributes = expr.pexp_attributes @ expansion.pexp_attributes }
;;
let ext extension_name =
Extension.V2.declare
(Extension_name.to_string extension_name)
Extension.Context.expression
Ast_pattern.(single_expr_payload __)
(expand extension_name)
;;
let () =
Ppx_driver.register_transformation "let"
~extensions:[
ext Bind;
ext Bind_open;
ext Map;
ext Map_open;
]
;;

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(* This signature is deliberately empty. *)

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module Monad_example = struct
module X : sig
type 'a t
module Let_syntax : sig
val return : 'a -> 'a t
val bind : 'a t -> ('a -> 'b t) -> 'b t
val map : 'a t -> f:('a -> 'b) -> 'b t
val both : 'a t -> 'b t -> ('a * 'b) t
module Open_on_rhs : sig val return : 'a -> 'a t end
module Open_in_body : sig val return : 'a -> 'a t end
end
end = struct
type 'a t = 'a
let return x = x
let bind x f = f x
let map x ~f = f x
let both x y = (x, y)
module Let_syntax = struct
let return = return
let bind = bind
let map = map
let both = both
module Open_on_rhs = struct let return = return end
module Open_in_body = struct let return = return end
end
end
module Let_syntax = X.Let_syntax
let _mf a : _ X.t =
let%bind_open x = a in
return (x + 1)
let _mf' a b c : _ X.t =
let%bind_open x = a and y = b and (u, v) = c in
return (x + y + (u * v))
let _mg a : _ X.t =
let%map x = a in
x + 1
let _mg' a b c : _ X.t =
let%map x = a and y = b and (u, v) = c in
x + y + (u * v)
let _mh a : _ X.t =
match%bind_open a with
| 0 -> return true
| _ -> return false
let _mi a : _ X.t =
match%map a with
| 0 -> true
| _ -> false
end
module Applicative_example = struct
module X : sig
type 'a t
module Let_syntax : sig
val return : 'a -> 'a t
val map : 'a t -> f:('a -> 'b) -> 'b t
val both : 'a t -> 'b t -> ('a * 'b) t
module Open_on_rhs : sig
val flag : int t
val anon : int t
end
module Open_in_body : sig end
end
end = struct
type 'a t = 'a
let return x = x
let map x ~f = f x
let both x y = (x, y)
module Let_syntax = struct
let return = return
let map = map
let both = both
module Open_on_rhs = struct
let flag = 66
let anon = 77
end
module Open_in_body = struct end
end
end
module Let_syntax = X.Let_syntax
(* {[
let _af a : _ X.t =
let%bind x = a in (* "Error: Unbound value Let_syntax.bind" *)
return (x + 1)
]} *)
(* {[
let _af' a b c : _ X.t =
let%bind x = a and y = b and (u, v) = c in (* "Error: Unbound value Let_syntax.bind" *)
return (x + y + (u * v))
]} *)
let _ag a : _ X.t =
let%map x = a in
x + 1
let _ag' a b c : _ X.t =
let%map x = a and y = b and (u, v) = c in
x + y + (u * v)
(* {[
let _ah a : _ X.t =
match%bind a with (* "Error: Unbound value Let_syntax.bind" *)
| 0 -> return true
| _ -> return false
]} *)
let _ai a : _ X.t =
match%map a with
| 0 -> true
| _ -> false
end
module Async_command_override_example = struct
module Deferred : sig
type 'a t
val return : 'a -> 'a t
module Let_syntax : sig
type 'a t
val return : 'a -> 'a t
val map : 'a t -> f:('a -> 'b) -> 'b t
val both : 'a t -> 'b t -> ('a * 'b) t
module Open_on_rhs : sig val return : 'a -> 'a t end
module Open_in_body : sig val return : 'a -> 'a t end
end with type 'a t := 'a t
end = struct
type 'a t = 'a
let return x = x
module Let_syntax = struct
let return = return
let map x ~f = f x
let both x y = (x, y)
module Open_on_rhs = struct let return = return end
module Open_in_body = struct let return = return end
end
end
module Command : sig
module Param : sig
type 'a t
val return : 'a -> 'a t
val flag : 'a -> int t
val anon : 'a -> int t
end
module Let_syntax : sig
type 'a t
val return : 'a -> 'a t
val map : 'a t -> f:('a -> 'b) -> 'b t
val both : 'a t -> 'b t -> ('a * 'b) t
module Open_on_rhs = Param
module Open_in_body : sig end
end with type 'a t := 'a Param.t
end = struct
module Param = struct
type 'a t = 'a
let return x = x
let map x ~f = f x
let both x y = (x, y)
let flag _ = 66
let anon _ = 77
end
module Let_syntax = struct
include Param
module Open_on_rhs = Param
module Open_in_body = struct end
end
end
module Command_override = struct
module Param = struct
include Command.Param
let special_flag = flag 88
end
module Let_syntax = struct
include (Command.Let_syntax : module type of Command.Let_syntax
with module Open_on_rhs := Command.Let_syntax.Open_on_rhs
and module Open_in_body := Command.Let_syntax.Open_in_body)
module Open_on_rhs = Param
module Open_in_body = struct
module Let_syntax = Deferred.Let_syntax
end
end
end
let _1 : int Command.Param.t =
let module Let_syntax = Command.Let_syntax in
[%map_open
let x = flag "foo"
and y = anon "bar"
in
x + y
]
;;
let _1 : (unit -> int Deferred.t) Command_override.Param.t =
let module Let_syntax = Command_override.Let_syntax in
[%map_open
let x = flag "foo"
and y = anon "bar"
and z = special_flag
in
(fun () ->
let%map () = Deferred.return () in
x + y + z)
]
;;
let _1 : (unit -> unit Deferred.t) Command.Param.t =
let module Let_syntax = Command_override.Let_syntax in
[%map_open
let () = return () in
fun () ->
let%map () = Deferred.return () in
()
]
;;
end