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Jeff 2023-12-02 00:16:00 -05:00
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@ -42,18 +42,18 @@ Dust is an interpreted, strictly typed language with first class functions. It e
- [Lists](#lists) - [Lists](#lists)
- [Maps](#maps) - [Maps](#maps)
- [Loops](#loops) - [Loops](#loops)
- [Tables](#tables)
- [Functions](#functions) - [Functions](#functions)
- [Concurrency](#concurrency) - [Concurrency](#concurrency)
- [Acknowledgements](#acknowledgements)
<!--toc:end--> <!--toc:end-->
## Features ## Features
- Simplicity: Dust is designed to be easy to learn. - Simplicity: Dust is designed to be easy to learn.
- Speed: Dust is built on [Tree Sitter] and [Rust] to prioritize performance and correctness. See [Benchmarks] below. - Speed: Dust is built on [Tree Sitter] and [Rust] to prioritize performance and correctness. See [Benchmarks] below.
- Concurrency: Easily and safely write code that runs in parallel. - Concurrency: A safe approach to parallelism.
- Safety: Written in safe, stable Rust. - Safety: Written in safe, stable Rust.
- Correctness: Type checking makes it easy to write good code that works. - Correctness: Type checking makes it easy to write good code.
## Usage ## Usage
@ -136,17 +136,16 @@ Variables have two parts: a key and a value. The key is always a string. The val
- string - string
- integer - integer
- floating point value - float
- boolean - boolean
- list - list
- map - map
- table
- function - function
Here are some examples of variables in dust. Here are some examples of variables in dust.
```dust ```dust
string = "The answer is 42." string = "foobar"
integer = 42 integer = 42
float = 42.42 float = 42.42
list = [1 2 string integer float] # Commas are optional when writing lists. list = [1 2 string integer float] # Commas are optional when writing lists.
@ -207,51 +206,18 @@ for number in list {
} }
``` ```
### Tables
Tables are strict collections, each row must have a value for each column. If a value is "missing" it should be set to an appropriate value for that type. For example, a string can be empty and a number can be set to zero. Dust table declarations consist of a list of column names, which are identifiers enclosed in pointed braces, followed by a list of rows.
```dust
animals = table <name species age> [
["rover" "cat" 14]
["spot" "snake" 9]
["bob" "giraffe" 2]
]
```
Querying a table is similar to SQL.
```dust
names = select name from animals
youngins = select species from animals {
age <= 10
}
```
The keywords `table` and `insert` make sure that all of the memory used to hold the rows is allocated at once, so it is good practice to group your rows together instead of using a call for each row.
```dust
insert into animals [
["eliza" "ostrich" 4]
["pat" "white rhino" 7]
["jim" "walrus" 9]
]
(assert_equal 6 (length animals))
```
### Functions ### Functions
Functions are first-class values in dust, so they are assigned to variables like any other value. Functions are first-class values in dust, so they are assigned to variables like any other value.
```dust ```dust
# This simple function has no arguments. # This simple function has no arguments.
say_hi = || => { say_hi = <fn> || {
(output "hi") (output "hi")
} }
# This function has one argument and will return a value. # This function has one argument and will return a value.
add_one = |number| => { add_one = <fn int -> int> |number| {
number + 1 number + 1
} }