Support for boolean ops (double &&, ||)

[toddmedema]

This is a JS library, after all :) Bites me almost every time I try to do an AND or OR

[josdejong]

Yeah, I understand that it would be convenient to have logical operators && and ||, since most of us are used to these from JavaScript or other programming languages.

The expression parser though tries to offer a math friendly syntax in the first place, not perse a JavaScript compatible one, though being able to keep the syntax consistent with JavaScript and Matlab for example is definitely a pre. I think the current logical operators and and or are way better than && and || because they are way easier to understand. Adding aliases && and || would not add value and make the API larger (and thus more complex). I'm therefore not sure if it's a good idea to add them, but if there are enough people in for it we can certainly consider it.

[tetslee]

I agree that the default syntax should be and and or, but it would be nice to be able to set aliases for operators and/or functions:

math.alias({
  operators: {
    and: '&&',
    or: '||'
  },
  functions: {
    log: 'ln',
    log10: 'log'
  }
})

e1 = math.parse('A && B')
e1.toString() // 'A && B'

e2 = math.parse('log(10)+ln(e)')
e2.eval() // 2

[josdejong]

Making it possible to let people configure their own behavior is an interesting idea.

In general though I think that "less is more", and more ways to do the same thing complicates an API, so I'm a bit careful and reserved in that regard.

Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away - Antoine de Saint-Exupery

:D

[FrankTabak]

Hi,
I know this post is a bit old, but I want to add my two cents.
First of; great library!
Regarding the operators and/or and ||/&&, I would ideally see the latter ones operate differently than the former ones.
Namely in the sense that they short-circuit, meaning that the second expression is not evaluated if the first one suffices to determine the outcome (e.g. suppose one has a || b, when a evaluates to true there is no need to evaluate b).

Consider the example following example. I have a variable a that can be either undefined, an empty string or a number.
Only in the latter case I want to perform operations on a.
The only way (that I found) to determine if the variable isn't undefined and an empty string is by stringing two conditional expressions together:

a = undefined
// undefined
a == undefined or equalText(a,'')
// TypeError: Unexpected type of argument in function compareText (expected: string or Array or Matrix, actual: undefined, index: 0)
a == undefined? true: equalText(a,'')
// true
a== undefined || equalText(a,'')
// SyntaxError: Value expected (char 17)

Using a short circuit operator in such a case would make the expression a lot easier.

[josdejong]

Namely in the sense that they short-circuit, meaning that the second expression is not evaluated if the first one suffices to determine the outcome (e.g. suppose one has a || b, when a evaluates to true there is no need to evaluate b).

Yes! That would would be very nice change/improvement. We already implemented this for the conditional operation (condition ? a : b). I think we should open a separate issue, and close this issue to keep it focused.

[sodik82]

I agree that the default syntax should be and and or, but it would be nice to be able to set aliases for operators and/or functions:

simple solution is just do string substitution

e1 = math.parse('A && B'.replaceAll('&&', 'and')