Add more docs for piping sources (#1053)

* Add more docs for piping sources

* Apply suggestions from code review

Co-authored-by: Alexandre Archambault <[email protected]>

Co-authored-by: Alexandre Archambault <[email protected]>

Author: Gedochao

website/docs/commands/basics.md

@@ -174,12 +174,23 @@ scala-cli hello.zip
 
 ## Piping
 
-You can also pipe Scala code to `scala-cli` for execution:
-
-```bash
-echo 'println("Hello")' | scala-cli -
-# Hello
-```
+You can also pipe code to `scala-cli` for execution:
+- scripts
+  ```bash
+  echo 'println("Hello")' | scala-cli _.sc
+  # Hello
+  ```
+- Scala code
+  ```bash
+  echo '@main def hello() = println("Hello")' | scala-cli _.scala
+  # Hello
+  ```
+- Java code
+  ```bash
+  echo 'class Hello { public static void main(String args[]) { System.out.println("Hello"); } }' | scala-cli _.java
+  # Hello
+  ```
+More details in the [Piping guide](../guides/piping.md).
 
 ## Scala CLI version
 

website/docs/guides/piping.md

@@ -0,0 +1,45 @@
+---
+title: Piping
+sidebar_position: 23
+---
+
+# Piping
+
+Instead of passing paths to your sources, you can also pipe your code via standard input:
+```bash
+echo '@main def hello() = println("Hello")' | scala-cli _
+# Hello
+```
+
+## Wildcards
+The `_` wildcard implies that the piped code is a standard Scala app.
+It is also possible to pass a script or Java code, when using the appropriate wildcard.
+The available options are as follows:
+- for standard Scala code use `_`, `_.scala` or `-.scala`;
+- for Scala scripts use `-`, `_.sc` or `-.sc`;
+- for Java code use `_.java` or `-.java`.
+
+## Examples
+- scripts
+```bash
+echo 'println("Hello")' | scala-cli _.sc
+# Hello
+```
+- Scala code
+```bash
+echo '@main def hello() = println("Hello")' | scala-cli _.scala
+# Hello
+```
+- Java code
+```bash
+echo 'class Hello { public static void main(String args[]) { System.out.println("Hello"); } }' | scala-cli _.java
+# Hello
+```
+
+## Mixing piped sources with on-disk ones
+It is also possible to pipe some code via standard input, while the rest of your code is on-disk.
+```bash
+echo 'case class HelloMessage(msg: String)' > HelloMessage.scala
+echo '@main def hello() = println(HelloMessage(msg = "Hello").msg)' | scala-cli _ HelloMessage.scala
+# Hello
+```