CompilerConfigurationSpec.md

ReScript build configuration

This document contains a list of all config parameters with remarks, and whether they are already implemented in rewatch. It is based on https://rescript-lang.org/docs/manual/latest/build-configuration-schema.

Parameter	JSON type	Remark	Implemented?
name	string		[x]
namespace	boolean		[x]
namespace	string		[x]
sources	string		[x]
sources	array of string		[x]
sources	Source		[x]
sources	array of Source		[x]
ignored-dirs	array of string		[_]
dependencies	array of string		[x]
dev-dependencies	array of string		[x]
generators	array of Rule-Generator		[_]
cut-generators	boolean		[_]
jsx	JSX		[x]
gentypeconfig	Gentype		[x]
compiler-flags	array of string		[x]
warnings	Warnings		[x]
ppx-flags	array of string		[x]
pp-flags	array of string		[_]
js-post-build	Js-Post-Build	Path respects in-source setting; stdout/stderr are logged	[x]
package-specs	array of Module-Format		[_]
package-specs	array of Package-Spec		[x]
entries	array of Target-Item		[_]
bs-external-includes	array of string		[_]
suffix	Suffix		[x]
reanalyze	Reanalyze	Reanalyze config; ignored by rewatch	[x]
experimental-features	ExperimentalFeatures		[x]
editor	object	VS Code tooling only; ignored by rewatch	[x]

Source

Parameter	JSON type	Remark	Implemented?
dir	string		[x]
type	"dev"		[x]
files	array of string		[_]
files	File-Object		[_]
generators	array of Build-Generator		[_]
public	"all"		[_]
public	array of string		[_]
resources	array of string		[_]
subdirs	boolean		[x]
subdirs	string		[_]
subdirs	array of string		[x]
subdirs	Source		[_]
subdirs	array of Source		[x]
group	string		[_]
group	Group		[_]
internal-depends	array of string		[_]

File-Object

Parameter	JSON type	Remark	Implemented?
slow-re	string		[_]
excludes	array of string		[_]

Build-Generator

Parameter	JSON type	Remark	Implemented?
name	string		[_]
edge	array of string		[_]

Rule-Generator

Parameter	JSON type	Remark	Implemented?
name	string		[_]
command	string		[_]

JSX

Parameter	JSON type	Remark	Implemented?
version	JSX-Version		[x]
module	"react"		[x]
mode	JSX-Mode		[x]
v3-dependencies	array of string		[x]

JSX-Version

enum: 3 | 4

JSX-Mode

enum: "classic" | "automatic"

Gentype

Parameter	JSON type	Remark	Implemented?
path	string		[_]

Reanalyze

Parameter	JSON type	Remark	Implemented?
analysis	array of Reanalyze-Analysis		[_]
suppress	array of string		[_]
unsuppress	array of string		[_]
transitive	boolean		[_]

Reanalyze-Analysis

enum: | "dce" | "exception" | "termination"

ExperimentalFeatures

An object of feature flags to enable experimental compiler behavior. Only supported by Rewatch.

• Keys: feature identifiers (PascalCase)
• Values: boolean (true to enable)

Currently supported features:

• LetUnwrap: Enable let? syntax.

Warnings

Parameter	JSON type	Remark	Implemented?
number	string		[x]
error	boolean		[x]
error	string		[x]

Js-Post-Build

Parameter	JSON type	Remark	Implemented?
cmd	string	Receives absolute path to JS file	[x]

The path passed to the command respects the in-source setting:

• in-source: true → path next to the source file (e.g., src/Foo.js)
• in-source: false → path in lib/<module>/ directory (e.g., lib/es6/src/Foo.mjs)

The command runs with the same working directory as the rewatch process (typically the project root).

stdout and stderr from the command are logged.

Package-Spec

Parameter	JSON type	Remark	Implemented?
module	Module-Format		[_]
in-source	boolean		[x]
suffix	Suffix		[_]

Module-Format

enum: "esmodule" | "commonjs"

default: "esmodule"

Suffix

enum: ".js" | ".mjs" | ".cjs" | ".bs.js" | ".bs.mjs" | ".bs.cjs"

Target-Item

Not really usable by ReScript, likely to be removed.

Parameter	JSON type	Remark	Implemented?
kind	Target-Item-Kind		[_]
main	string		[_]

Target-Item-Kind

enum: "native" | "bytecode" | "js"

Group

What is this even for? The spec says it is not even implemented in ReScript. Likely to be removed.

Parameter	JSON type	Remark	Implemented?
name	string		[_]
hierarchy	boolean		[_]