Data Model
How data is described and referenced in Fenl.
Fenl operates on typed values. Fenl's type system describes several different kinds of values.
Simple values such as the string "hello" or the integer 57 are scalar types.
Types may be combined to create records. Record fields may be scalar or record types.
Scalars
Scalar types include booleans, numbers, strings, timestamps, durations and calendar intervals.
Type | Examples | Description |
|---|---|---|
|
| Booleans represent true or false |
|
| Unsigned integer numbers of a particular bit size. |
|
| Signed integer numbers of a particular bit size. |
|
| Floating point numbers. When using a decimal a leading numeric character is required. |
|
| Unicode strings. Strings are written with double-quotes. Double quotes may be escaped within the string. |
|
| The point in time a given number of seconds, milliseconds, microseconds or nanoseconds after the Unix Epoch (00:00:00 UTC on January 1, 1970). |
|
| A given number of seconds, milliseconds, microseconds or nanoseconds. |
|
| A calendrical interval. |
Records
Records allow combining multiple different types into a single value. Records are unnamed - any two records with the same set of fields and value types are considered equal. Fields within a record may have different types. Field names must start with a letter.
Type | Examples | Description |
|---|---|---|
|
| A record is a composite type made up of 0 or (generally) more components. Each component is associated with a |
Type Coercion
Fenl implicitly coerces numeric types when different kinds of numbers are combined. For example adding a 64-bit signed integer value to a 32-bit floating point value produces a 64-point floating point value.
Type Promotion Rules
Type coercion will never produce an integer overflow or reduction in numeric precision. Such conversions may be explicitly specified using as.
The coercion rules can be summarized with the following rules:
- Integers can be widened:
i8 -> i16 -> i32 -> i64. - Unsigned integers can be widened:
u8 -> u16 -> u32 -> u64. - Floating point numbers can be widened:
f16 -> f32 -> f64. - Unsigned integers can be promoted to the next wider integer
u8->i16,u16 -> i32,u32 -> i64. - All numbers may be converted to
f64. - Strings may be implicitly converted to timestamps by attempting to parse them as RFC3339 values. The timestamp will be
nullfor strings that don't successfully parse.
Numeric Type Coercion Table
When two numbers are used, Fenl attempts to promote them to a compatible type as the smallest type that both types may be converted to.
The following table shows the result of this promotion for pairs of numeric types.
| i8 | i16 | i32 | i64 | u8 | u16 | u32 | u64 | f16 | f32 | f64 | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| i8 | i8 | i16 | i32 | i64 | i16 | i32 | i64 | f64 | f16 | f32 | f64 |
| i16 | i16 | i16 | i32 | i64 | i16 | i32 | i64 | f64 | f16 | f32 | f64 |
| i32 | i32 | i32 | i32 | i64 | i16 | i32 | i64 | f64 | f16 | f32 | f64 |
| i64 | i64 | i64 | i64 | i64 | i64 | i64 | i64 | f64 | f16 | f32 | f64 |
| u8 | i16 | i16 | i16 | i64 | u8 | u16 | u32 | u64 | f16 | f32 | f64 |
| u16 | i32 | i32 | i32 | i64 | u16 | u16 | u32 | u64 | f16 | f32 | f64 |
| u32 | i64 | i64 | i64 | i64 | u32 | u32 | u32 | u64 | f16 | f32 | f64 |
| u64 | f64 | f64 | f64 | f64 | u64 | u64 | u64 | u64 | f16 | f32 | f64 |
| f16 | f16 | f16 | f16 | f16 | f16 | f16 | f16 | f16 | f16 | f32 | f64 |
| f32 | f32 | f32 | f32 | f32 | f32 | f32 | f32 | f32 | f32 | f32 | f64 |
| f64 | f64 | f64 | f64 | f64 | f64 | f64 | f64 | f64 | f64 | f64 | f64 |
️ Coercion to Floating-Point
Note that when
u64is combined with a signed type the result isf64. This is the only case where an operation between integers produces a floating-point value.
Updated about 1 month ago