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Gleam

typed BEAM services friendly functional programming and reliable APIs

English

Definition first

What Gleam means

Gleam is a programming language for writing exact instructions, often used for typed BEAM services friendly functional programming and reliable APIs. Start with one mental model: input goes through steps and becomes output.

Minimum run factsFile src/main.gleamRun gleam runHabit Use pattern matching and simple typed data before processes
Program

An ordered set of instructions. It reads input, follows rules, and produces output.

Value and variable

A value is data. A variable is the name you use to hold and reuse that data.

Function

A named piece of work. It takes input, does one job, and can return a result.

Runtime

Gleam is the place that actually runs code from src/main.gleam.

First readable code

Program output

entry point output syntax io.println
io.println("42")
Output 42

Language lineage

Gleam family tree

See where Gleam comes from, which languages feel close, and what to learn next.

roots
ErlangElixirML
currentGleamTyped BEAM family
familyTyped BEAM family
best used for

typed concurrent services on the BEAM runtime

Zero base path

1Read one rule2Predict output3Type from memory4Run checklist5Repeat with one change

Question bank

Search before practice

Pick a stage or search across the open programming bank. Jump straight to the matching drill.

18 matching questions
Q 1ChoiceStage 1 definitions

Gleam practice 1

Gleam question 1. Choose the statement that matches printing a value.

Q 2ChoiceStage 1 definitions

Gleam practice 2

Gleam question 2. Choose the statement that matches naming a value.

Q 3ChoiceStage 1 definitions

Gleam practice 3

Gleam question 3. Choose the statement that matches reusable function.

Q 4ChoiceStage 1 definitions

Gleam practice 4

Gleam question 4. Choose the statement that matches basic collection.

Q 5ChoiceStage 1 definitions

Gleam practice 5

Gleam question 5. Choose the statement that matches printing a value.

Q 6ChoiceStage 1 definitions

Gleam practice 6

Gleam question 6. Choose the statement that matches naming a value.

Q 7ChoiceStage 1 definitions

Gleam practice 7

Gleam question 7. Choose the statement that matches reusable function.

Q 8ChoiceStage 1 definitions

Gleam practice 8

Gleam question 8. Choose the statement that matches basic collection.

Q 9ChoiceStage 1 definitions

Gleam practice 9

Gleam question 9. Choose the statement that matches printing a value.

Q 10ChoiceStage 1 definitions

Gleam practice 10

Gleam question 10. Choose the statement that matches naming a value.

Q 11ChoiceStage 1 definitions

Gleam practice 11

Gleam question 11. Choose the statement that matches reusable function.

Q 12ChoiceStage 1 definitions

Gleam practice 12

Gleam question 12. Choose the statement that matches basic collection.

Q 13ChoiceStage 1 definitions

Gleam practice 13

Gleam question 13. Choose the statement that matches printing a value.

Q 14ChoiceStage 1 definitions

Gleam practice 14

Gleam question 14. Choose the statement that matches naming a value.

Q 15ChoiceStage 1 definitions

Gleam practice 15

Gleam question 15. Choose the statement that matches reusable function.

Q 16ChoiceStage 1 definitions

Gleam practice 16

Gleam question 16. Choose the statement that matches basic collection.

Q 17ChoiceStage 1 definitions

Gleam practice 17

Gleam question 17. Choose the statement that matches printing a value.

Q 18ChoiceStage 1 definitions

Gleam practice 18

Gleam question 18. Choose the statement that matches naming a value.

Multiple choice

Gleam practice 1

Q 1Choicenew

Gleam question 1. Choose the statement that matches printing a value.

io.println("42")

Reference

Patterns for src/main.gleam

Gleamgleam run
Recall from memoryRead a small point then write it back without looking
Trace the codeWrite variable values line by line before you run the answer
Type it yourselfCopy less type more and fix one small error at a time

entry point output syntax io.println

Program output

io.println("42")
  • Run the smallest file first
  • Print one known value
  • Check the output before adding more code

variables assignment types let

Values and names

let total = 42
io.println(int.to_string(total))
  • Give values readable names
  • Keep one idea per line while learning
  • Trace the value before changing it

function collection List

Functions and collections

fn add(a: Int, b: Int) -> Int {
  a + b
}

let scores = [40, 2]
io.println(int.to_string(list.length(scores)))
  • Keep functions small
  • Return useful values
  • Use the common collection before reaching for frameworks