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slate

Quick Start

This guide creates a typed table, writes two values, reads one back, and closes the table automatically.

1. Add slate to your project

Section titled “1. Add slate to your project”
Terminal window
gleam add slate

2. Open a table and store data

Section titled “2. Open a table and store data”
import gleam/dynamic/decode
import gleam/result
import slate/set


pub fn main() {
  use users <- set.with_table(
    "data/users.dets",
    key_decoder: decode.string,
    value_decoder: decode.int,
  )
  use Nil <- result.try(set.insert(users, "alice", 42))
  use Nil <- result.try(set.insert(users, "bob", 37))
  set.lookup(users, key: "alice")
}
// Ok(42), and the table is closed

use users <- set.with_table(...) passes the rest of main as a callback. with_table opens the file before that callback and closes it when the callback returns. The decoders make reads fail explicitly if the terms on disk are not strings and integers.

3. Data persists across restarts

Section titled “3. Data persists across restarts”
import gleam/dynamic/decode
import slate/set


pub fn write() {
  use table <- set.with_table(
    "data/state.dets",
    key_decoder: decode.string,
    value_decoder: decode.int,
  )
  set.insert(table, "counter", 42)
}


pub fn read() {
  use table <- set.with_table(
    "data/state.dets",
    key_decoder: decode.string,
    value_decoder: decode.int,
  )
  set.lookup(table, key: "counter")
}

Run write, stop the node, then run read: it returns Ok(42) from the same file.

Next steps

Section titled “Next steps”