pippianders/cash

Really safe money

Status

Ready to try out! This is not used in production anywhere yet, and the docs are incomplete, so try it out with the appropriate amount of caution.

Features

• No partial functions.
• No silently incorrect functions.
• Compile errors for instances that must not exist
• Batteries included, otherwise users will write their own batteries, incorrectly

Comparison

	Really Safe Money	Safe Money	Dollaridoos	Plutus values	Simple Amount	Safe Decimal	Money	Simple Money
Explicitly meant for money	✔️	✔️	✔️	✔️	✖️	✖️	✔️	✔️
Cannot create or destroy money through errors	✔️	✔️	C	✔️	✔️	✔️	✔️	✖️
No silent overflow or underflow	✔️	✔️	C	✔️	✔️	✔️	✔️	✖️
Cannot represent nonsense values of money	✔️	✔️	C	✔️	✖️	C	✔️	✖️
Computations use constant time and space	✔️	✖️	C	✖️	✖️	C	✖️	✔️
Cannot represent amounts that are too granular	✔️	✖️	C	✔️	✖️	C	✖️	✖️
No-floating-point representation	✔️	✔️	C	✔️	✔️	✔️	✔️	✖️
Fixed-sized representation	✔️	✖️	C	✖️	✖️	C	✖️	✔️
Amounts with type-level currency	✔️	✔️	C [1]	✖️	✔️	✖️	✔️[2]	✔️
Amounts without type-level currency	✔️	✖️	C	✔️	✖️	✔️	✖️	✖️
A type for positive-only amounts	✔️	✖️	C	✖️	✖️	✔️	✔️	✖️
A type for positive or negative amounts	✔️	✔️	C	✔️	✔️	✔️	✖️	✔️
No 'Num' instance for amounts	✔️	✖️	✖️	✔️	✖️	✖️	✖️	✔️
Type-errors for instances that must not exist	✔️	✔️	✖️	✖️	✖️	✖️	✖️	✖️
Multi-amounts	🚧	✖️	✖️	✔️	✖️	✖️	✖️	✖️
Addition	✔️	✔️	✔️	✖️	✔️	✔️	✔️	✔️
Subtraction	✔️	✔️	✔️	✖️	✔️	✔️	✔️	✔️
Integer scalar multiplication	✔️	✔️	✔️	✖️	✖️	✖️	✔️	✔️
Distribution	✔️	✖️	✖️	✖️	✔️	✖️	✖️	✖️
Fractional multiplication	✔️	✔️	✔️	✖️	✔️	✔️	✔️	✔️
Fractional multiplication with correct accounting	✔️	✖️	✖️	✖️	✖️	✖️	✖️	✖️

[1]: Dollaridoos technically supports multiple currencies, but its Show instance always uses $.

[2]: Money technically supports multiple currencies, but only the three that it defines.

(I will happily correct any errors in this table if you see I have made any.)

• ✔️: Supported
• C: Possible but you have to write some code yourself. This is not good enough for a money library.
• 🚧: Under development
• ✖️: Not supported
• ?: I don't know.

License

All rights reserved. Contact me if you would like to use this library.