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I would like a language with real-world data types, with units and automatic unit conversion and checking. Along with Ada-style-ish value limitations (e.g. variable must be positive, or between 0 and 100, etc.)

> length i = 12 inches

> length h = 1 foot

> i * h

area 1 square_foot

> square_inches(ih)

area 144 square_inches

> hours(ih)

error: type mismatch

Time and money, as well (currency conversion not required)

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You can already implement this in any language with strong typing, like C++ or Rust or OCaml or Haskell. I guess the syntax might be more verbose, so you would have to write inches(12) rather than 12 inches.

C++ has user defined literals, so you could write 12_inch.

The formal term for the Ada-ish constraints on acceptable values is dependent types.

Wait no, it's close but not as strong as dependent types. I was thinking of Agda.

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