let bindings and scope

let is Tide’s way to name a value. You can think of it as “pin this value to a name so I can use it later.”

Basic bindings

let answer = 42
query answer
query answer + 1

You can bind any expression:

let xs = [1, 2, 3, 4, 5]
let squares = [x * x for x in xs]

query squares

Or bind a dictionary (record-like value):

let person = {name: "Alice", age: 30}
query person.name

Tide currently has a simple model:

let bindings at the top level are available to later code in the same file.
Comprehension variables (like x in [... for x in ...]) are local to that comprehension.

Example:

let xs = [1, 2, 3]
query [x + 1 for x in xs]

// `x` is not available here.
// query x

When exploring the language, it’s totally normal to write:

That style makes Tide feel like a programmable notebook.