feat!: add temporal extension literals

API.md

@@ -151,8 +151,11 @@ Untyped scalar extension literals such as `2` or `'path'` are represented as
 scalar `ExtensionValue` variants and render without expression type suffixes,
 even in verbose output. The same values can still be requested as `Expr` through
 `ArgsExtractor`, which widens them to default non-nullable Substrait literal
-expressions. Typed literals, field references, function calls, and casts are
-represented as expression values.
+expressions. Temporal typed literals such as `'2024-01-01':date` or
+`'2024-01-01T12:34:56.123456':precisiontimestamp<6>` are represented as
+`ExtensionLiteral` values and can also be requested as `Expr`. Other typed
+literals, field references, function calls, and casts are represented as
+expression values.
 
 `ExtensionProtoConvert` converts between extension arguments and Substrait
 protobuf values in either direction, such as output columns and relation

GRAMMAR.md

@@ -239,11 +239,11 @@ A literal can be an integer, float, boolean, string, or null. Literals may inclu
 - **`null`**` := "null"`
   - Examples: `null:i64?`, `null:string?`, `null:date?`
   - A type annotation is required for `null`
-- **`typed_literal`**` := string ":" type`
-  - String literals with type annotations for non-primitive types
-  - Examples: `'2023-01-01':date`, `'2023-12-25T14:30:45.123':timestamp`
+- **typed literal syntax**` := (float / integer / boolean / string / "null") ":" type`
+  - Literals with explicit type annotations, including string literals for non-primitive types
+  - Examples: `'2023-01-01':date`, `'2023-12-25T14:30:45.123':timestamp`, `'2023-12-25T14:30:45.123456789':precisiontimestamp<9>`
 
-All basic literal types (`integer`, `float`, `boolean`, and `string`) are supported, plus `date`, `time`, `timestamp`, and typed null literals. Other Substrait literal types (e.g., `interval_year`, `decimal`, `uuid`) are not yet implemented.
+All basic literal types (`integer`, `float`, `boolean`, `string`, and typed `null`) are supported, plus `date`, `time`, `timestamp`, `precisiontime<N>`, `precisiontimestamp<N>`, and `precisiontimestamptz<N>` typed literals. Other Substrait literal types (e.g., `interval_year`, `decimal`, `uuid`) are not yet implemented.
 
 ## Types
 
@@ -309,6 +309,9 @@ Root[result]
 ### Compound Types
 
 Compound types follow the same syntax as standard Substrait parameterized types.
+Precision temporal types use one integer parameter for precision:
+`precisiontime<N>`, `precisiontimestamp<N>`, and `precisiontimestamptz<N>`,
+where `N` is between `0` and `12`.
 
 #### Examples
 
@@ -959,9 +962,11 @@ Untyped scalar extension arguments such as `2`, `2.4`, `true`, and `'path'`
 are treated as extension scalar values and render without expression type
 suffixes, even in verbose output. They can still be consumed by extension
 handlers as expressions, in which case they widen to default non-nullable
-Substrait literal expressions. Typed literals such as `2:i16` or
-`'2024-01-01':date`, field references, function calls, and casts are expression
-values.
+Substrait literal expressions. Temporal typed literals such as
+`'2024-01-01':date` and
+`'2024-01-01T12:34:56.123456':precisiontimestamp<6>` are extension literal
+values and can also widen to expression values. Other typed literals such as
+`2:i16`, field references, function calls, and casts are expression values.
 
 #### Examples