Lea Language
Quick Start
let numbers = [1, 2, 3, 4, 5]
let result = numbers
/> filter((x) -> x > 2)
/> map((x) -> x * x)
/> reduce(0, (acc, x) -> acc + x)
result /> print
Core Principles
- Pipes:
value /> fn passes value as first arg; use input placeholder to control position
- Functions:
let double = (x) -> x * 2 (no fn keyword)
- Multi-statement bodies: Indentation-based or brace-delimited
{ }
- Decorators: Trailing
#log #memo #time #retry(3) etc. after function body
- Bindings:
let x = 10 immutable, maybe x = 0 mutable
- Records:
{ name: "Max", age: 99 } with member access record.field
- Contexts:
context Name = default + provide Name value + @Name attachments
Builtins
- Math:
sqrt, abs, floor, ceil, round, min, max
- Lists:
length, head, tail, push, concat, map, filter, reduce, range
- IO:
print (returns first arg for chaining)
- Async:
delay(ms) — promise that resolves after ms
Running
npm run repl # Interactive REPL
npm run lea file.lea # Run a file
Reference Files
- references/syntax.md - Full syntax reference
- references/architecture.md - Interpreter internals
1---2name: lea3description: Use when writing or modifying Lea code - pipe-oriented functional language with tree-walk interpreter4---5
6# Lea Language
7
8## Quick Start
9
10```lea
11let numbers = [1, 2, 3, 4, 5]
12
13let result = numbers
14 /> filter((x) -> x > 2)
15 /> map((x) -> x * x)
16 /> reduce(0, (acc, x) -> acc + x)
17
18result /> print
19```
20
21## Core Principles
22
23- **Pipes**: `value /> fn` passes value as first arg; use `input` placeholder to control position
24- **Functions**: `let double = (x) -> x * 2` (no fn keyword)
25- **Multi-statement bodies**: Indentation-based or brace-delimited `{ }`
26- **Decorators**: Trailing `#log #memo #time #retry(3)` etc. after function body
27- **Bindings**: `let x = 10` immutable, `maybe x = 0` mutable
28- **Records**: `{ name: "Max", age: 99 }` with member access `record.field`
29- **Contexts**: `context Name = default` + `provide Name value` + `@Name` attachments
30
31## Builtins
32
33- Math: `sqrt`, `abs`, `floor`, `ceil`, `round`, `min`, `max`
34- Lists: `length`, `head`, `tail`, `push`, `concat`, `map`, `filter`, `reduce`, `range`
35- IO: `print` (returns first arg for chaining)
36- Async: `delay(ms)` — promise that resolves after ms
37
38## Running
39
40```bash
41npm run repl # Interactive REPL
42npm run lea file.lea # Run a file
43```
44
45## Reference Files
46
47- [references/syntax.md](references/syntax.md) - Full syntax reference
48- [references/architecture.md](references/architecture.md) - Interpreter internals
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