Conversions¶

Some types in NDCell are implicitly converted (coerced) to other types when used with various operators or passed to functions.

Subtype coercion¶

Some types are subtypes of other types; this is implemented by coercing the subtype to the supertype when necessary. For example, a Cell is implicitly converted to a CellSet when used where a CellSet is required. Here are the rules for subtype coercion:

The CellSet coerced from a Cell contains only that cell state
The CellSet coerced from a Tag contains all cell states with a truthy value for that tag
The PatternFilter coerced from a Pattern accepts only that pattern

Boolean conversion¶

Values of some types can be converted to a boolean, which is represented using an Int. This can happen implicitly (when used in a place where a boolean is required) or explicitly (using bool()).

An Int is truthy if it is not equal to 0.
A Cell is truthy if it is not equal to #0.
A Vec is truthy if any of its components is not equal to 0.
A Pattern is truthy if any of its cells is not equal to #0.

“Truthy” values become TRUE (1) and “falsey” values (anything not truthy) become FALSE (0).

Vector to vector conversion¶

A Vec of one length can be converted to a Vec of a different length. This can happen implicitly (when used in a place where a Vec of a different length is required) or explicitly (using vec()).

If the new length is shorter than the original length, the vector is truncated and extra components are removed.
- Example: vec2([10, 20, 30, 40]) → [10, 20]
If the new length is longer than the original length, the vector is extended with zeros.
- Example: vec4([10, 20]) → [10, 20, 0, 0]

Integer to vector conversion¶

An Int can be converted to a Vec of any length. This can happen implicitly (when used in a place where a Vec is required) or explicitly (using vec()).

A new vector is constructed with the value of the original integer for each component.

Example: vec3(-5) → [-5, -5, -5]