pass and fail examples

crates/compiler/parse/src/parser.rs

@@ -1,4 +1,4 @@
-use crate::state::State;
+use crate::{ast::Pattern, state::State};
 use bumpalo::collections::vec::Vec;
 use bumpalo::Bump;
 use roc_region::all::{Loc, Position, Region};
@@ -1519,6 +1519,45 @@ where
     }
 }
 
+/// # Example
+/// ```rust
+/// # use roc_parse::state::{State};
+/// # use crate::roc_parse::parser::{Parser, Progress, word};
+/// # use roc_region::all::Position;
+/// # use bumpalo::Bump;
+/// # #[derive(Debug, PartialEq)]
+/// # enum Problem {
+/// #     NotFound(Position),
+/// # }
+/// # fn foo() {
+/// #   let arena = Bump::new();
+///     let parser = word("hello", Problem::NotFound);
+///     let (progress, m, state) = parser.parse(&arena, State::new("hello, world".as_bytes()), 0).unwrap();
+///     assert_eq!(progress, Progress::MadeProgress);
+///     assert_eq!(m, ());
+///     assert_eq!(state.pos(), Position::new(5));
+/// # }
+/// ```
+///
+/// ```rust
+/// # use roc_parse::state::{State};
+/// # use crate::roc_parse::parser::{Parser, Progress, word};
+/// # use roc_region::all::Position;
+/// # use bumpalo::Bump;
+/// # #[derive(Debug, PartialEq)]
+/// # enum Problem {
+/// #     NotFound(Position),
+/// # }
+/// # fn foo() {
+/// #   let arena = Bump::new();
+///     let parser = word("bye", Problem::NotFound);
+///     let actual = parser.parse(&arena, State::new("hello, world".as_bytes()), 0).map(|(a,b,_)| (a,b));
+///     assert_eq!(
+///         actual,
+///         Err((Progress::NoProgress, Problem::NotFound(Position::zero()))),
+///     );
+/// # }
+/// ```
 pub fn word<'a, ToError, E>(word: &'static str, to_error: ToError) -> impl Parser<'a, (), E>
 where
     ToError: Fn(Position) -> E,