Question 1

How do I convert meters to miles in Idris using Quantities?

Accepted Answer

Use the 'convertTo' function, e.g., 'convertTo Mile distanceInMeters', where 'distanceInMeters' is a measurement in meters. The library ensures type-safe conversion based on predefined unit definitions like 'Mile' as 1609.344 meters.

Question 2

Quantities vs F# units of measure: which is better for scientific computing?

Accepted Answer

Quantities provides compile-time safety via dependent types in Idris, offering stronger guarantees but in a niche ecosystem. F#'s units of measure are more integrated with .NET and have better tooling, but rely on type inference with fewer compile-time checks for complex derivations.

Question 3

Can I use Quantities for real-time game physics?

Accepted Answer

Yes, the README includes an example for game physics with screen units like 'Pixel' and 'Pxs'. However, performance may vary due to Idris's dependent type overhead, and real-time constraints might favor optimized, low-level libraries.

Question 4

How to define a custom unit like 'light-year' in Quantities?

Accepted Answer

Define it as an elementary unit using syntax like '< one "light-year" equals 9460730472580800 Metre >', referencing existing units. This allows type-safe conversions and operations within the library's framework.

Question 5

What's the performance impact of using Quantities in Idris?

Accepted Answer

Dependent types can introduce compile-time overhead and potentially runtime inefficiencies, though Idris aims for efficient code generation. For performance-critical applications, benchmarking is advised, as the library adds abstraction layers.

Question 6

Is Quantities compatible with Idris 2 or newer versions?

Accepted Answer

The README only mentions testing with Idris 1.3.1, so compatibility with Idris 2 is uncertain. Users may need to adapt the code or check for updates, as dependent type systems can have breaking changes between versions.

quantities

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