@kha, the implementation is a little bit hackish. It is whitespace
sensitive to avoid `f @g`, an application with argument `@g` to be
parsed as a named pattern.
Here are other approaches I have considered:
1- In the `namedPattern`, we add a guard that ensures the pattern
is *not* an identifier. Thus, `f @g` would not be considered a valid
`namedPattern`. Drawback: we would always try to parse it as a
namedPattern first, fail, and then try as an application.
2- Enforce whitespace before application arguments. Drawback: `f(a+b)`
would not be a valid application anymore.
0dcdc2c198