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https://github.com/oppiliappan/eva

a calculator REPL, similar to bc(1)
https://github.com/oppiliappan/eva

calculator cli hacktoberfest rust

Last synced: 12 days ago
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a calculator REPL, similar to bc(1)

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![heroimg.png](https://u.peppe.rs/6G.png)

# eva

simple calculator REPL, similar to `bc(1)`, with syntax highlighting and persistent history

![eva.png](https://u.peppe.rs/kP.png)

### installation

- Homebrew
```shell
$ brew install eva
```

- crates.io
```shell
$ cargo install eva
```

- manual
```shell
$ git clone https://github.com/nerdypepper/eva
$ cd eva
$ cargo run
```

### usage

```shell
eva 0.3.1
NerdyPepper
Calculator REPL similar to bc(1)

USAGE:
eva [OPTIONS] [INPUT]

ARGS:
Optional expression string to run eva in command mode

OPTIONS:
-b, --base Radix of calculation output (1 - 36) [default: 10]
-f, --fix Number of decimal places in output (1 - 64) [default: 10]
-h, --help Print help information
-r, --radian Use radian mode
-V, --version Print version information

```

type out an expression and hit enter, repeat.

```shell
> 1 + sin(30)
1.5
> floor(sqrt(3^2 + 5^2))
5
> 5sin(45) + cos(0)
4.53553
```

### updating

- crates.io
```shell
$ cargo install eva --force
```

- manual
```shell
$ cargo install --force --path /path/to/eva
```

### operators

- binary operators: `+ - * / ^ **`
- unary operators: `+ -`

### constants

some constants available in rust standard library.

```
e pi
```

examples:
```
pi * 5^2 # πr²
```

### functions

all trigonometric functions expect input in degrees.

```
1 argument:
sin cos tan csc sec cot sinh cosh tanh
asin acos atan acsc asec acot ln log2 log10
sqrt ceil floor abs

2 arguments:
log nroot

deg(x) - convert x to degrees
rad(x) - convert x to radians
```

examples:
```
sqrt(sin(30)) # parentheses are mandatory for functions

log10100 # no
log10(100) # yes

log(1, 10) # function with two arguments
```

### quality of life features

- auto insertion of `*` operator
```
>12sin(45(2)) # 12 * sin(45 * (2))
12
```

- auto balancing of parentheses
```
>ceil(sqrt(3^2 + 5^2 # ceil(sqrt(3^2 + 5^2))
6
```

- use previous answer with `_`
```
> sin(pi)
0.0548036650
> _^2
0.0030034417
>
```

- super neat error handling
```
> 1 + ln(-1)
Domain Error: Out of bounds!
```

- syntax highlighting

### todo

- ~~add support for variables (pi, e, _ (previous answer))~~
- ~~syntax highlighting~~
- ~~multiple arg functions~~
- ~~screenshots~~
- ~~create logo~~
- ~~unary operators (minus, plus)~~
- ~~add detailed error handler~~
- ~~add unit tests~~
- ~~lineditor~~ with syntax highlighting
- ~~add more functions~~

### contributors

the rust community has helped eva come a long way, but these devs deserve a
special mention for their contributions:

[Ivan Tham](https://github.com/pickfire)
[Milan Marković](https://github.com/hepek)
[asapokl](https://github.com/kzoper)