Lowbar

A utility-belt plugin for the ARO language that gives you 71 qualifiers and 5 actions for working with collections, objects, types, and values — all expressed in plain language.

Lowbar turns common data operations into single ARO statements. Filter a list, reshape an object, check a type, generate a sequence — no boilerplate, no ceremony.

Create the <users> with [
    { name: "Alice", age: 30, role: "admin" },
    { name: "Bob",   age: 25, role: "user" },
    { name: "Eve",   age: 22, role: "user" }
].

Compute the <admins: lowbar.matching> from the <users> with { role: "admin" }.
Compute the <names: lowbar.pluck> from the <admins> with { field: "name" }.
(* names = ["Alice"] *)

Compute the <sorted: lowbar.sortby> from the <users> with { field: "age" }.
Compute the <youngest: lowbar.first> from the <sorted>.
(* youngest = { name: "Eve", age: 22, role: "user" } *)

Installation

With the ARO package manager

aro add https://github.com/arolang/Lowbar.git

Manual

Copy the Plugins/lowbar/ directory into your ARO application's Plugins/ folder:

MyApp/
├── main.aro
└── Plugins/
    └── lowbar/
        ├── plugin.yaml
        ├── Package.swift
        └── Sources/
            └── LowbarPlugin.swift

ARO discovers and compiles the plugin automatically on first run.

How It Works

Lowbar provides two kinds of tools:

Qualifiers

Qualifiers transform values inline using the <result: handle.qualifier> syntax. The handle is lowbar:

Compute the <reversed: lowbar.reverse> from the <items>.

Many qualifiers accept parameters through a with { } clause:

Compute the <top-three: lowbar.first> from the <items> with { n: 3 }.
Compute the <sorted: lowbar.sortby> from the <users> with { field: "age" }.

Qualifiers also work inside expressions:

Log <items: lowbar.reverse> to the <console>.

Actions

Actions are verb-based statements that generate new data. The handle is Lowbar (PascalCase):

Lowbar.Range the <numbers> with { stop: 10 }.
Lowbar.Random the <dice> with { min: 1, max: 6 }.

Quick Reference

Collections (39 qualifiers)

Qualifier	Description	Example
first	First element, or first N	<x: lowbar.first> / with { n: 3 }
last	Last element, or last N	<x: lowbar.last> / with { n: 2 }
rest	Everything after the first	<x: lowbar.rest> / with { n: 3 }
initial	Everything before the last	<x: lowbar.initial> / with { n: 2 }
compact	Remove falsy values	<x: lowbar.compact>
flatten	Flatten nested lists	<x: lowbar.flatten> / with { deep: false }
uniq	Remove duplicates	<x: lowbar.uniq> / with { field: "id" }
shuffle	Random reorder (Fisher-Yates)	<x: lowbar.shuffle>
sample	Random element(s)	<x: lowbar.sample> / with { n: 3 }
size	Count elements/chars/keys	<x: lowbar.size>
reverse	Reverse list or string	<x: lowbar.reverse>
toarray	Convert to array	<x: lowbar.toarray>
sortby	Sort by field	with { field: "age" } / with { order: "desc" }
groupby	Group by field	with { field: "role" }
countby	Count per group	with { field: "status" }
indexby	Build lookup object	with { field: "id" }
pluck	Extract one field	with { field: "name" }
matching	Filter by properties	with { role: "admin", active: true }
findwhere	First match	with { role: "admin" }
rejectwhere	Inverse filter	with { role: "admin" }
partition	Split into [pass, fail]	with { active: true }
max	Maximum value or by field	<x: lowbar.max> / with { field: "age" }
min	Minimum value or by field	<x: lowbar.min> / with { field: "age" }
includes	Check membership	with { value: 42 }
every	All match?	with { active: true }
some	Any match?	with { role: "admin" }
without	Remove specific values	with { values: [3, 5, 7] }
union	Combine (unique)	with { other: [4, 5, 6] }
intersection	Common values	with { other: [3, 4, 5] }
difference	Values not in other	with { other: [3, 4, 5] }
zip	Pair at positions	with { other: [1, 2, 3] }
unzip	Transpose pairs	<x: lowbar.unzip>
object	Pairs to object	<x: lowbar.object>
chunk	Split into chunks	with { size: 3 }
indexof	Find position	with { value: "x" }
last-indexof	Find last position	with { value: "x" }
sortedindex	Insertion point	with { value: 5 }
findindex	Index by properties	with { role: "admin" }
findlast-index	Last index by properties	with { role: "admin" }

Numeric (3 qualifiers)

Qualifier	Description	Example
sum	Sum numeric values	<total: lowbar.sum>
avg	Average of values	<mean: lowbar.avg>
reduce	Fold with operation	with { op: "+" } / with { op: "*" } / with { op: "join", separator: ", " }

Objects (14 qualifiers)

Qualifier	Description	Example
keys	All keys (sorted)	<k: lowbar.keys>
values	All values	<v: lowbar.values>
pairs	To [[key, value], ...]	<p: lowbar.pairs>
invert	Swap keys and values	<inv: lowbar.invert>
pick	Keep specified keys	with { keys: ["name", "email"] }
omit	Remove specified keys	with { keys: ["password"] }
defaults	Fill missing keys	with { timeout: 30, debug: false }
extend	Merge (overwrite)	with { port: 9090, debug: true }
clone	Shallow copy	<copy: lowbar.clone>
has	Key exists?	with { key: "host" }
get	Nested dot path	with { path: "user.address.city" }
findkey	Find key by value	with { value: "#ff0000" }
mapobject	Rename keys	with { old: "firstName", new: "name" }
ismatch	Has properties?	with { host: "localhost" }

Type Checks (9 qualifiers)

Qualifier	Description
isempty	True for [], "", {}, nil
isarray	True for lists
isstring	True for strings
isnumber	True for Int or Double
isboolean	True for booleans
isobject	True for objects/dicts
isnull	True for nil
isfinite	True for finite numbers
isequal	Deep equality: with { other: 42 }

Utility (6 qualifiers)

Qualifier	Description	Example
identity	Pass-through	<same: lowbar.identity>
escape	HTML-escape	<safe: lowbar.escape>
unescape	Reverse HTML-escape	<raw: lowbar.unescape>
join	List to string	with { separator: ", " }
split	String to list	with { separator: ":" }
tap	Pass-through (debug)	<x: lowbar.tap>

Actions (5)

Action	Description	Example
Range	Generate integer list	Lowbar.Range the <n> with { stop: 10 }.
Random	Random integer	Lowbar.Random the <n> with { min: 1, max: 6 }.
UniqueId	Unique identifier	Lowbar.UniqueId the <id> with { prefix: "u_" }.
Now	Unix timestamp (ms)	Lowbar.Now the <ts> for the <system>.
Times	Repeat a value	Lowbar.Times the <stars> with { n: 5, value: "*" }.

Testing

aro test .

The tests/ directory contains 67 test files with 155 test cases covering all Lowbar functions.

Building from Source

cd Plugins/lowbar
swift build -c release

Requires Swift 6.2+, ARO 0.9.1+, and the ARO Plugin SDK.

Acknowledgments

Lowbar is a clone of Underscore.js by Jeremy Ashkenas and the many contributors who have maintained it since 2009. The function names, semantics, and organization are modeled directly after underscore's API, adapted to ARO's declarative qualifier syntax. Thank you to the underscore.js team for their outstanding work for the JavaScript community — Lowbar carries that spirit into the ARO community.

License

MIT