Rush

Rust shell. Inspired by Ion.

In case you're reading this: rush is in the works and not a priority. Features may be missing even if defined below.

Syntax

; is 'alias' for new line.

Syntax and type errors crash the program.

Scopes are for each block. Functions won't have access to variables it wouldn't have access if it wasn't a function:

fn testing
    echo $t
end

if true
    testing # Error! t is not defined
end

Variables

String variables using $, arrays using @.

Assigned using let. Left side is evaluated to a string as well. Variable names must be valid ascii characters, or part of namespace (namespace::var syntax).

let a = d
let $b = c
echo $d # c

Arrays are assigned using [ var ]. You can join arrays and strings by simply passing them there, like [ $var @var ].

All assignments are done via the let keyword. Instead of =, other operations are supported:

• *= - multiply
• += - addition
• -= - substraction
• /= - division
• //= - int division
• %= - modulo
• ::= - append
• @@= - prepend

Special variables

env:: namespace contains the environment (and doesn't error out if the variable doesn't exist, instead, empty string is returned) color:: (alias c::) has a number of colors

Types

Based on the value set in the set let (the one with just =), a type is infered (unless specificaly set using let x:type = ...). This type is then used for the operations after.

Supported types:

• i32 (alias int)
• i64
• i128
• u32
• u64
• u128
• f32
• f64
• str
• hmap[T] (where T is one of the other types, except array)
• [T] (where T is one of the other types, except hmap)

HashMap is basically array, but with string keys (instead of numbers) in random order.

Return

Sets the exit code (and possibly exits function/script early). If no return is set, the return code is set to the return code of the last expression.

Math

Using $(()) syntax. Math priority applies. Brackets are supported. Variables used without their prepender. Indexing is possible.

String and Array methods

• $trim(str) - Trims the string (both sides)
• $trimLeft(str) - Trims the string (start/left)
• $trimright(str) - Trims the string (end/right)
• $escape(str) - Escapes string
• $unescape(str) - Unescapes string
• @split(str by) - Splits str by by into array
• @join(str by=" ") - Joins str together by

Slices: [x..y] gets a substring (or subarray) of the variable. When x ommited, defaults to 0 (the start). When y ommited, defaults to end.

Control

Bracketless. Scopes are ended by the keyword end.

if - Runs it's scope if the command returns 0. Useful in pair with test builtin. for $val of @arr - Runs for each value of the array (or hashmap) for $val of ... - Runs for each number in the range. while - Runs in loop as long as the command returns 0

Functions

Defined by fn name arg -- desc. arg can be ommited, or repeated. desc will be printed when the arg is missing (or when describe command is used).

Special

From config (defined by ~/.rushrc), special functions can be defined.

• PROMPT will be run to render the prompt
• HIGHLIGHT will run (for each key - make it fast) to highlight the text.

Builtins

• let for assigning variables
• export for exporting variables to env
• test tests for evaluation (= for equality, >, <, <=, >= for number comparisons)
• exists for existance of a given string, or if given a flag (-Functions, -variables, -env, -file, -directory, -readable file, -writable file, e-xecutable file), existence of the selected object
• true returns 0
• false returns 1

Some GNU standard utils may be overwritten by rush builtins, but must be made compatible.