Merge pull request #6952 from ageron/improve-result-chaining-doc

Improve Result-chaining documentation

roc-for-elm-programmers.md

@@ -931,6 +931,8 @@ foo 1 2 if something then 3 else 4
 
 ## Backpassing
 
+Note: the backpassing syntax will likely be replaced with a new `?` operator in the future, see [this discussion](https:/roc-lang/roc/issues/6828) for more details.
+
 Suppose I'm using a platform for making a CLI, and I want to run several
 `Task`s in a row which read some files from the disk. Here's one way I could do
 that, assuming `Task.await` is like Elm's `Task.andThen` with arguments flipped:

www/content/tutorial.md

@@ -819,6 +819,20 @@ Result.isOk (List.get ["a", "b", "c"] 1)
 # Note: There's a Result.isErr function that works similarly.
 ```
 
+```roc
+Result.try (Str.toU64 "2") \idx -> List.get ["a", "b", "c", "d"] idx
+# returns `Ok "c"`
+
+# Notes:
+# - `Str.toU64 "2"` parses the string "2" to the integer 2, and returns `Ok 2` (more on
+# integer types later)
+# - since parsing is successful, `Result.try` passes 2 to the function `\idx -> ...`
+# - passing "abc" or "1000" instead of "2" would have resulted in `Err InvalidNumStr`
+# or `Err OutOfBounds` respectively
+```
+
+`Result.try` is often used to chain functions that can fail (as in the example above), returning the first error if any occurs. There is [a discussion](https:/roc-lang/roc/issues/6828) to add syntax sugar for such chaining.
+
 ### [Walking the elements in a list](#walking-the-elements-in-a-list) {#walking-the-elements-in-a-list}
 
 We've now seen a few different ways you can transform lists. Sometimes, though, there's nothing