Wrong return type inference

[dvd101x]

Some functions / methods assume that if the input is of a certain type the output will be of the same type.

math.matrix([1], 'dense', 'number').map(x=>math.unit(x,'m'))
// results in a DenseMatrix of units of type number

Maybe the dispatch system could also include information on the type that will be returned for a certain input.

math.typed('unit', {
 'number, string -> unit': (num, str) => math.unit(num, str)
})

[gwhitney]

Indeed, the efforts Jos and I have been making on a new core engine for mathjs (see e.g. https://code.studioinfinity.org/StudioInfinity/nanomath) explicitly include return type annotations on all mathjs functions. The primary motivation is that then implementations of the functions can be assembled that don't re-check the types on every internal call, which saves a lot of time.

Since this is unlikely to be addressed short of an engine overhaul, moving to Discussions.