Zolo Cheatsheet

let x = 10              // immutable
let mut y = 0           // mutable
const PI = 3.14         // constant

int    f64    str    bool    nil
[int]                   // array
{str: int}              // map
(int, str)              // tuple
int?                    // optional
fn(int) -> int          // function type
Map<str, int>           // generic

fn add(a: int, b: int) -> int { a + b }
let double = |x| x * 2                     // lambda
fn apply(f: fn(int) -> int, x: int) -> int { f(x) }

if cond { } else if cond2 { } else { }
let x = if cond { a } else { b }           // if expression
if let Some(v) = opt { use(v) }            // if let
match val { 0 => "zero", _ => "other" }

for i in 0..10 { }             // exclusive range
for i in 0..=10 { }            // inclusive range
for item in list { }            // iterate
for (i, v) in pairs { }        // destructure
while cond { }
while let Some(x) = iter() { } // while let
loop { break }

struct Point { x: f64, y: f64 }
let p = Point { x: 1.0, y: 2.0 }
impl Point { fn dist(self) -> f64 { ... } }

enum Color { Red, Green, Blue }
enum Shape { Circle(f64), Rect(f64, f64) }
let s = Shape::Circle(5.0)

trait Display { fn show(self) -> str }
impl Display for Point { fn show(self) -> str { "..." } }

match value {
    0 => "zero",
    n if n < 0 => "negative",
    Shape::Circle(r) => "circle {r}",
    Point { x, y } => "({x},{y})",
    'a' | 'b' => "ab",
    _ => "other",
}

// Arithmetic:   + - * / % **
// Comparison:   == != < > <= >=
// Logical:      && || !
// Assignment:   = += -= *= /= %=
// Pipe:         |>      a |> f() → f(a)
// Tap:          &.      a &. f() → f(a); a
// Optional:     ?.      a?.b → nil if a is nil
// Coalesce:     ??      a ?? b → b if a is nil
// Propagate:    ?       expr? → early return on error
// Spread:       ...     [...a, ...b]
// Range:        ..      0..10 (exclusive)
// Range incl:   ..=     0..=10 (inclusive)

"Hello, {name}!"                 // interpolation
"""multiline"""                  // multiline
sql"SELECT * FROM t WHERE id={x}" // tagged template

@test      fn test_it() { ... }  // test function
@memoize   fn fib(n) { ... }     // cached results
@deprecated("msg") fn old() { }  // deprecation warning
@builder   struct Config { ... }  // builder pattern

// String
string.trim(s)  string.split(s, sep)  string.contains(s, sub)

// Array
Array.map(a, f)  Array.filter(a, f)  Array.reduce(a, f, init)
Array.push(a, v) Array.len(a)  Array.sort(a)

// Map
Map.new()  Map.set(m, k, v)  Map.get(m, k)  Map.keys(m)

// Set
Set.from(arr)  Set.add(s, v)  Set.has(s, v)  Set.union(a, b)

// Option
Option.Some(v)  Option.None()  Option.unwrap_or(o, def)

// Result
Result.Ok(v)  Result.Err(e)  Result.unwrap(r)

// Iterator
Iter.from(a) |> Iter.map(f) |> Iter.filter(f) |> Iter.collect()

zolo run file.zolo           # run
zolo compile file.zolo       # show Lua output
zolo check file.zolo         # type check only
zolo test file.zolo          # run @test functions
zolo fmt file.zolo           # format
zolo repl                    # interactive REPL