Emoji based error handling

text/0000-emoji-based-error-handling.md

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+- Feature Name: emoji_based_error_handling
+- Start Date: 2016-04-01
+- RFC PR: (leave this empty)
+- Rust Issue: (leave this empty)
+- RFC Authors: [@dbrgn][DB], [@dns2utf8][SS], [@rnestler][RN]
+
+
+# Summary
+[summary]: #summary
+
+This RFC proposes to implement emoji based error handling in Rust.
+
+
+# Motivation
+[motivation]: #motivation
+
+Emoji have become an universal way of expressing emotions. Error handling in is
+generally a very emotional topic in software development. Therefore error
+handling and the use of emoji are a perfect match.
+
+Furthermore, after the introduction of the question mark postfix operator in
+[RFC 243][1] (Trait-based exception handling), a lot of people raised concerns
+that error handling is not visible enough in the code anymore. Using colorful
+emoji to denote error handling would certainly make it obvious that errors are
+being handled.
+
+
+# Detailed design
+[design]: #detailed-design
+
+**Description**
+
+The cornerstones of Rust error handling are two enums: `Result` and `Option`. A
+`Result<T, E>` may either be `Success<T>` or `Err(E)` while an `Option(T)` may
+be either `Some(T)` or `None`.
+
+```rust
+enum Result<T, E> {
+    Ok(T),
+    Err(E),
+}
+enum Option<T> {
+    Some(T),
+    None,
+}
+```
+
+We suggest that these error types are complemented by emoji based alternatives.
+
+A `Result` is an expression of hope for a certain outcome (:pray:, U+1F64F). If
+the operation succeeds, developers party (:beers:, U+1F37B), but sometimes shit
+happens (:poop:, U+1F4A9).
+
+```rust
+enum 🙏<T, E> {
+    🍻<T>,
+    💩<E>,
+}
+```
+
+On the other hand, an `Option` is an expression of uncertainty (:interrobang:,
+U+203D).  Something might be there (:raising_hand:, U+1F64B) or it might not be
+(:x:, U+274C).
+
+```rust
+enum ‽<T> {
+    🙋<T>,
+    ❌,
+}
+```
+
+**Matching**
+
+These emoji can be matched as usual:
+
+```rust
+fn i_am_a_teapot(which_kind: ‽<TeaType>) -> 🙏<Tea, String> {
+    match which_kind {
+        🙋(kind) => 🍻(kind.brew()),
+        ❌ => 💩("Not specified which kind of tea to brew."),
+    }
+}
+```
+
+**Unwrapping and Macros**
+
+Another often used error handling mechanism is the `try!` macro. We suggest
+using the :muscle: emoji to bring across the notion of strength or trust. Yes
+we try!
+
+When the developer is too lazy to do proper error handling, he/she may also use
+the `unwrap()` method. We suggest replacing it with the see-no-evil emoji
+(:see_no_evil:).
+
+Last but not least, when all else fails, code may panic (:scream:).
+
+```rust
+if let 🙋(coffee) = brew() {
+    println!("Drinking {} coffee", coffee.rate_taste().🙈());
+    💪!(coffee.drink());
+} else {
+    😱!("406 - WE'RE OUT OF COFFEE!!1");
+}
+```
+
+**Feature Gate**
+
+As with other newly proposed features, we propose adding a feature gate for emojified error handling:
+
+```rust
+#[feature(emojification)]
+```
+
+**Implementation**
+
+The Rust grammar already fully supports UTF8. There are two ways to implement this:
+
+- Modify the `IDENTIFIER` grammar to include unicode characters. Currently
+  identifiers may only contain ASCII letters and underscores. 
+- Implement a syntax extension that operates on the token tree and that
+  replaces all occurrences of certain emoji with their regular ASCII
+  counterparts.
+
+
+# Drawbacks
+[drawbacks]: #drawbacks
+
+None, although the proposal might seem less convincing on other days of the year.
+
+
+# Alternatives
+[alternatives]: #alternatives
+
+Alternative Result emoji choices have been suggested:
+
+- Proposal (:ring:) with success (:heart:) or no success (:broken_heart:)
+- Fear (:fearful:) with yay (:sparkles:) or nay (:skull:)
+
+
+
+# Unresolved questions
+[unresolved]: #unresolved-questions
+
+- Not all commonly used fonts and text editors offer full support of all
+  required Unicode characters. But that problem could be resolved trivially
+  by developing our own fully featured `rust.ttf` font and `rustty` terminal
+  emulator.
+- So far, a syntax extension to implement support for the proposed features has
+  not yet been written and published.
+
+
+
+[1]: https://github.com/rust-lang/rfcs/pull/243
+[DB]: https://github.com/dbrgn
+[SS]: https://github.com/dns2utf8
+[RN]: https://github.com/rnestler