tembrel/expressions

Java framework for evaluating, formatting, and parsing double-precision arithmetic expressions with constants, variables, unary and binary operations, and binding of variables to other expressions

Hi there 👋

W.I.P.

expressions's Issues

Allow bound variable to be unused in let-expression

It's harmless, and it allows the sam Map of bindings to be used with different expressions without fear of exception.

Equivalency

Add note to readme about implementing equivalency of expressions, either through structural analysis or by repeatedly randomly assigning free variables to see if the resulting values are the same.

Rename and eliminate methods

• Method evaluate() should be value().
• No need for format(), just use toString().
• parse() could be of() (and could take varargs array of operator enum types, hiding ExpressionParser).

BasicOperator.SQUARED is superflous and has parsing problems

a^23 is parsed not as a ^ 23 but as a^2 * 3. There's really no need for BasicOperator.SQUARED except to provide an example of a postfix operator.

Use Java double-precision arithmetic semantics

There's no good reason not to rely on the underlying Java double-precision arithmetic semantics in this API. Two things (at least) would need to be changed:

1. Don't throw DivisionByZeroException at all.
2. Don't throw IllegalArgumentException when NaN passed to expr(...).