An RPN calculator with array operations and quotations.

```
<> $ 4 5 +
<9> $ p
9
<> $ [3 4 5] 6 x
<[18 24 30]> $ 0 swap
<[18 24 30]> $ (+) /
<72> $ p
72
<> 
```

# Usage 

       ec <expression>: evaluate <expression> as a sequence of
                        ec commands and print the resulting stack.
       ec             : enter interactive (repl) mode.
   

   ec operates as a RPN desk calculator with quotation
   and vector math functions. Ordinarily, tokens are
   evaluated from left to right as they're pushed onto
   the stack. eg.,

       3 4 +

   will push 3, then 4, then apply the operation +, which
   will pop two elements from the stack, add them, and
   push their sum.

   To quote a sequence of tokens, wrap it in
   parentheses. eg.,

       (3 4 +)

   will push a single quotation containing just those
   three tokens, which can be applied by subsequent
   commands.

   To create a vector, enclose a sequence of numbers or
   other vectors in square brackets. eg.,

       [3 4]

   will create a 1-dimensional vector and push it on the
   stack.

   Vectors can be added to other vectors or individual
   numbers. eg.,
 
       [3 4] 2 +

   will add 2 to each element of [3 4], resulting in
   [5 6].

       [3 4] [2 1] +

   will add matching elements of vectors, resulting in
   [5 5].

   Vectors can be of arbitrary dimension, but must
   contain homogeneous data. eg.,

       [[2 1] [0 0]]

   is a valid vector (of shape [2 2]), but

       [[2] [0 0]]

   is not.

   For a full dictionary listing, enter the special
   command:

       ??

   To get a description of any word, quote it and use the
   special command. eg.,

       (!) ?

   Will print a description of the `apply` adverb.

# Installation

On Arch Linux, install `ec` via AUR:

`yay -S ec`

On other systems, install the [Janet][] language, clone this
repository and build using `jpm`:

```
$ mkdir janet_modules
$ JANET_PATH=janet_modules/ jpm load-lockfile
$ JANET_PATH=janet_modules/ jpm build
$ cp build/ec <somewhere on your path>
```

[Janet]: https://janet-lang.org