Lesson 1 — Your first program

You are here

1. Your first program ←
2. Values and variables
3. Making decisions
4. Repeating things
5. Functions
6. Lists and hashes
7. Strings
8. Organizing programs
9. Classes

What are we learning?

You will write one instruction, run it, and see text appear.

A program is a list of instructions for the computer.

An instruction is one step, like “print this sentence.”

The smallest useful program

say("Hello, Echo!");

What each part means

Piece	Meaning
say	Tell Echo to print something
( ... )	The thing to print goes inside
"Hello, Echo!"	Text (words) — always in quotes
;	End of this instruction

Output

Hello, Echo!

How to run it

In the Playground

1. Open the Playground.
2. Wait until status shows Ready.
3. Make sure the left side contains the line above (or choose the Hello example).
4. Click Run.
5. Read the OUTPUT panel on the right.

On your computer

1. Save the line in a file named hello.echo.
2. In Terminal, go to that folder.
3. Run:

elang hello.echo

(See Install Echo if elang is not set up yet.)

Try it — change the message

Change the text inside the quotes to your name, for example:

say("Hello, Ada!");

Expected output:

Hello, Ada!

Run it again. You just changed an Echo program.

Fix it — missing semicolon

This is wrong (no ; at the end):

say("Hello, Echo!")

Echo stops and says it expected ;.

Add the semicolon and run again.

What you learned

• A program is a list of instructions.
• say prints text.
• Text goes in quotes.
• Instructions end with ;.

Next

→ Lesson 2 — Values and variables

Also: Choose your path · Common mistakes