`|` (pipe) has the highest precedence, contradicting the README; `{{= user.name | uppercase() }}` fails to parse #20

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opened 2026-08-07 13:33:05 +02:00 by Hemera · 0 comments

Hemera commented

2026-08-07 13:33:05 +02:00

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The README states: "The | operator has the lowest precedence of the operators."

In src/parser/mod.rs:973 the pipe is registered as Left(99). Winnow's Pratt parser treats higher numbers as tighter binding, so | is currently the tightest operator — above postfix ?/[ (23) and . (22).

Consequences (both verified against main):

{{= user.name | uppercase() }} → parse error. The . parses its rhs at min-power 23, but | (99) binds tighter, so the rhs becomes name | uppercase(), which the Dot rhs-restriction rejects.
{{= foo | f().name }} parses as (foo | f()).name (opposite of what "lowest precedence" implies).

Fix: give | the lowest precedence (e.g. below || at 7). Then user.name | uppercase() parses as (user.name) | uppercase() while foo? | or_default("Unknown") still works (? is postfix, binds tighter).

The README states: *"The `|` operator has the lowest precedence of the operators."* In `src/parser/mod.rs:973` the pipe is registered as `Left(99)`. Winnow's Pratt parser treats higher numbers as tighter binding, so `|` is currently the **tightest** operator — above postfix `?`/`[` (23) and `.` (22). Consequences (both verified against `main`): - `{{= user.name | uppercase() }}` → **parse error**. The `.` parses its rhs at min-power 23, but `|` (99) binds tighter, so the rhs becomes `name | uppercase()`, which the Dot rhs-restriction rejects. - `{{= foo | f().name }}` parses as `(foo | f()).name` (opposite of what "lowest precedence" implies). Fix: give `|` the lowest precedence (e.g. below `||` at 7). Then `user.name | uppercase()` parses as `(user.name) | uppercase()` while `foo? | or_default("Unknown")` still works (`?` is postfix, binds tighter).

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2026-08-07 13:34:42 +02:00

Hemera referenced this issue from a pull request that will close it,

2026-08-07 13:39:11 +02:00

Set correct lowest precedence for the pipe operator #27

Hemera closed this issue

2026-08-07 13:41:16 +02:00