Document formal script syntax (#5336)

Signed-off-by: Ben Sherman <[email protected]>
Signed-off-by: Christopher Hakkaart <[email protected]>
Signed-off-by: Paolo Di Tommaso <[email protected]>
Co-authored-by: Christopher Hakkaart <[email protected]>
Co-authored-by: Paolo Di Tommaso <[email protected]>

docs/channel.md

@@ -52,7 +52,7 @@ process foo {
 
 workflow {
   result = foo(1)
-  result.view { "Result: ${it}" }
+  result.view { file -> "Result: ${file}" }
 }
 ```
 

docs/config.md

@@ -22,37 +22,65 @@ You can use the `-C <config-file>` option to use a single configuration file and
 
 ## Syntax
 
-A Nextflow configuration file is a simple text file containing a set of properties defined using the syntax:
+The Nextflow configuration syntax is based on the Nextflow script syntax. It is designed for setting configuration options in a declarative manner while also allowing for dynamic expressions where appropriate.
+
+A Nextflow config file may consist of any number of *assignments*, *blocks*, and *includes*. Config files may also contain comments in the same manner as scripts.
+
+See {ref}`syntax-page` for more information about the Nextflow script syntax.
+
+### Assignments
+
+A config assignment consists of a config option and an expression separated by an equals sign:
 
 ```groovy
-name = value
+workDir = 'work'
+docker.enabled = true
+process.maxErrors = 10
 ```
 
-Please note, string values need to be wrapped in quotation characters while numbers and boolean values (`true`, `false`) do not. Also note that values are typed. This means that, for example, `1` is different from `'1'` — the former is interpreted as the number one, while the latter is interpreted as a string value.
+A config option consists of an *option name* prefixed by any number of *scopes* separated by dots. Config scopes are used to group related config options. See {ref}`config-options` for the full set of config options.
+
+The expression is typically a literal value such as a number, boolean, or string. However, any expression can be used:
 
-### Variables
+```groovy
+params.helper_file = "${projectDir}/assets/helper.txt"
+```
 
-Configuration properties can be used as variables in the configuration file by using the usual `$propertyName` or `${expression}` syntax.
+### Blocks
 
-For example:
+A config scope can also be specified as a block, which may contain multiple configuration options. For example:
 
 ```groovy
-propertyOne = 'world'
-anotherProp = "Hello $propertyOne"
-customPath = "$PATH:/my/app/folder"
+// dot syntax
+docker.enabled = true
+docker.runOptions = '-u $(id -u):$(id -g)'
+
+// block syntax
+docker {
+    enabled = true
+    runOptions = '-u $(id -u):$(id -g)'
+}
 ```
 
-Please note, the usual rules for {ref}`string-interpolation` are applied, thus a string containing a variable reference must be wrapped in double-quote chars instead of single-quote chars.
+As a result, deeply nested config options can be assigned in various ways. For example, the following three assignments are equivalent:
 
-The same mechanism allows you to access environment variables defined in the hosting system. Any variable name not defined in the Nextflow configuration file(s) is interpreted to be a reference to an environment variable with that name. So, in the above example, the property `customPath` is defined as the current system `PATH` to which the string `/my/app/folder` is appended.
+```groovy
+executor.retry.maxAttempt = 5
 
-### Comments
+executor {
+    retry.maxAttempt = 5
+}
 
-Configuration files use the same conventions for comments used by the Groovy or Java programming languages. Thus, use `//` to comment a single line, or `/*` .. `*/` to comment a block on multiple lines.
+executor {
+    retry {
+        maxAttempt = 5
+    }
+}
+```
 
 ### Includes
 
-A configuration file can include one or more configuration files using the keyword `includeConfig`. For example:
+A configuration file can include any number of other configuration files using the `includeConfig` keyword:
 
 ```groovy
 process.executor = 'sge'
@@ -62,7 +90,11 @@ process.memory = '10G'
 includeConfig 'path/foo.config'
 ```
 
-When a relative path is used, it is resolved against the actual location of the including file.
+Relative paths are resolved against the location of the including file.
+
+:::{note}
+Config includes can also be specified within config blocks. However, config files should only be included at the top level or in a [profile](#config-profiles) so that the included config file is valid on its own and in the context in which it is included.
+:::
 
 ## Constants
 
@@ -79,22 +111,6 @@ The following constants are globally available in a Nextflow configuration file:
 `projectDir`
 : The directory where the main script is located.
 
-## Config scopes
-
-Configuration settings can be organized in different scopes by dot prefixing the property names with a scope identifier, or grouping the properties in the same scope using the curly brackets notation. For example:
-
-```groovy
-alpha.x = 1
-alpha.y = 'string value..'
-
-beta {
-     p = 2
-     q = 'another string ..'
-}
-```
-
-See {ref}`config-options` for the full list of config settings.
-
 (config-params)=
 
 ## Parameters

docs/developer/plugins.md

@@ -7,6 +7,8 @@ This page describes how to create, test, and publish third-party plugins.
 
 The best way to get started with your own plugin is to refer to the [nf-hello](https://github.com/nextflow-io/nf-hello) repository. This repository provides a minimal plugin implementation with several examples of different extension points and instructions for building, testing, and publishing.
 
+Plugins can be written in Java or Groovy.
+
 The minimal dependencies are as follows:
 
 ```groovy
@@ -151,7 +153,7 @@ Refer to the source code of Nextflow's built-in executors to see how to implemen
 :::{versionadded} 22.09.0-edge
 :::
 
-Plugins can define custom Groovy functions, which can then be included into Nextflow pipelines.
+Plugins can define custom functions, which can then be included in Nextflow pipelines.
 
 To implement a custom function, create a class in your plugin that extends the `PluginExtensionPoint` class, and implement your function with the `Function` annotation:
 

docs/dsl1.md

@@ -88,7 +88,7 @@ In DSL1, the entire Nextflow pipeline must be defined in a single file (e.g. `ma
 DSL2 introduces the concept of "module scripts" (or "modules" for short), which are Nextflow scripts that can be "included" by other scripts. While modules are not essential to migrating to DSL2, nor are they mandatory in DSL2 by any means, modules can help you organize a large pipeline into multiple smaller files, and take advantage of modules created by others. Check out the {ref}`module-page` to get started.
 
 :::{note}
-With DSL2, the Groovy shell used by Nextflow also imposes a 64KB size limit on pipeline scripts, so if your DSL1 script is very large, you may need to split your script into modules anyway to avoid this limit.
+DSL2 scripts cannot exceed 64 KB in size. Large DSL1 scripts may need to be split into modules to avoid this limit.
 :::
 
 ## Deprecations

docs/index.md

@@ -111,6 +111,7 @@ fusion
 :caption: Reference
 :maxdepth: 1
 
+reference/syntax
 reference/cli
 reference/config
 reference/env-vars

docs/module.md

@@ -2,15 +2,15 @@
 
 # Modules
 
-In Nextflow, a **module** is a script that may contain functions, processes, and workflows (collectively referred to as *components*). A module can be included in other modules or pipeline scripts and even shared across workflows.
+Nextflow scripts can include **definitions** (workflows, processes, and functions) from other scripts. When a script is included in this way, it is referred to as a **module**. Modules can be included by other modules or pipeline scripts and can even be shared across workflows.
 
 :::{note}
 Modules were introduced in DSL2. If you are still using DSL1, see the {ref}`dsl1-page` page to learn how to migrate your Nextflow pipelines to DSL2.
 :::
 
 ## Module inclusion
 
-A component defined in a module script can be imported into another Nextflow script using the `include` keyword.
+You can include any definition from a module into a Nextflow script using the `include` keyword.
 
 For example:
 
@@ -23,7 +23,7 @@ workflow {
 }
 ```
 
-The above snippet imports a process named `foo`, defined in the module script, into the main execution context. This way, `foo` can be invoked in the `workflow` scope.
+The above snippet imports a process named `foo`, defined in the module, into the main execution context. This way, `foo` can be invoked in the `workflow` scope.
 
 Nextflow implicitly looks for the script file `./some/module.nf`, resolving the path against the *including* script location.
 
@@ -57,7 +57,7 @@ Module directories allow the use of module scoped binaries scripts. See [Module
 
 ## Multiple inclusions
 
-A Nextflow script can include any number of modules, and an `include` statement can import any number of components from a module. Multiple components can be included from the same module by using the syntax shown below:
+A Nextflow script can include any number of modules, and an `include` statement can import any number of definitions from a module. Multiple definitions can be included from the same module by using the syntax shown below:
 
 ```groovy
 include { foo; bar } from './some/module'
@@ -73,7 +73,7 @@ workflow {
 
 ## Module aliases
 
-When including a module component, it's possible to specify an *alias* with the `as` keyword. Aliasing allows you to avoid module name clashes, by assigning them different names in the including context. For example:
+When including definition from a module, it's possible to specify an *alias* with the `as` keyword. Aliasing allows you to avoid module name clashes, by assigning them different names in the including context. For example:
 
 ```groovy
 include { foo } from './some/module'
@@ -85,7 +85,7 @@ workflow {
 }
 ```
 
-You can even include the same component multiple times under different names:
+You can also include the same definition multiple times under different names:
 
 ```groovy
 include { foo; foo as bar } from './some/module'
@@ -96,13 +96,15 @@ workflow {
 }
 ```
 
+(module-params)=
+
 ## Module parameters
 
 :::{deprecated} 24.07.0-edge
-As a best practice, parameters should be used in the entry workflow and passed to functions / processes / workflows as explicit inputs.
+As a best practice, parameters should be used in the entry workflow and passed to workflows, processes, and functions as explicit inputs.
 :::
 
-A module script can define parameters using the same syntax as a Nextflow workflow script:
+A module can define parameters using the same syntax as a Nextflow workflow script:
 
 ```groovy
 params.foo = 'Hello'
@@ -182,9 +184,9 @@ Ciao world!
 
 ## Module templates
 
-The module script can be defined in an external {ref}`template <process-template>` file. The template file can be placed in the `templates` directory where the module script is located.
+Process script {ref}`templates <process-template>` can be included alongside a module in the `templates` directory.
 
-For example, suppose we have a project L with a module script that defines two processes, P1 and P2, both of which use templates. The template files can be made available in the local `templates` directory:
+For example, suppose we have a project L with a module that defines two processes, P1 and P2, both of which use templates. The template files can be made available in the local `templates` directory:
 
 ```
 Project L
@@ -208,15 +210,15 @@ Pipeline B
 └── main.nf
 ```
 
-With the possibility to keep the template files inside the project L, A and B can use the modules defined in L without any changes. A future project C would do the same, just cloning L (if not available on the system) and including its module script.
+With the possibility to keep the template files inside the project L, A and B can use the modules defined in L without any changes. A future project C would do the same, just cloning L (if not available on the system) and including its module.
 
 Beside promoting the sharing of modules across pipelines, there are several advantages to keeping the module template under the script path:
 
-1. module components are *self-contained*,
-2. module components can be tested independently from the pipeline(s) that import them,
-3. it is possible to create libraries of module components.
+1. Modules are self-contained
+2. Modules can be tested independently from the pipeline(s) that import them
+3. Modules can be made into libraries
 
-Ultimately, having multiple template locations allows a more structured organization within the same project. If a project has several module components, and all of them use templates, the project could group module scripts and their templates as needed. For example:
+Having multiple template locations enables a structured project organization. If a project has several modules, and they all use templates, the project could group module scripts and their templates as needed. For example:
 
 ```
 baseDir

docs/overview.md

@@ -95,11 +95,9 @@ Read the {ref}`executor-page` to learn more about the Nextflow executors.
 
 ## Scripting language
 
-Nextflow is designed to have a minimal learning curve, without having to pick up a new programming language. In most cases, users can utilise their current skills to develop Nextflow workflows. However, it also provides a powerful scripting DSL.
+Nextflow is a workflow language based on [Java](https://en.wikipedia.org/wiki/Java_(programming_language)) and [Groovy](https://groovy-lang.org/). It is designed to simplify writing scalable and reproducible pipelines. In most cases, users can leverage their existing programming skills to develop Nextflow pipelines without the steep learning curve that usually comes with a new programming language.
 
-Nextflow scripting is an extension of the [Groovy programming language](<http://en.wikipedia.org/wiki/Groovy_(programming_language)>), which in turn is a super-set of the Java programming language. Groovy can be considered as Python for Java in that it simplifies the writing of code and is more approachable.
-
-Read the {ref}`script-page` section to learn about the Nextflow scripting language.
+See {ref}`script-page` for more information about the Nextflow scripting language.
 
 ## Configuration options