This course is the shortest complete route from zero Lispex experience to writing and testing a small decision rule. It has six lessons, and the sidebar walks through them in the order below. Each lesson builds on the previous one, ends with a small exercise, and tells you when you are ready to move on.
Before you begin
Use any modern browser for the Playground. Local installation is optional in the first lesson. When you install, the page gives both npm and Native paths. Every lesson is short, and you can stop after any of them.
The course uses one reading rule repeatedly.
(operation input1 input2 ...)Parentheses do not mean mysterious Lisp punctuation. They show a form. Most
forms call a procedure. A small named set such as define, if, and quote
controls evaluation.
If the parentheses still feel unfamiliar, spend five minutes with Reading the Parentheses before Step 1. It has no prerequisites and returns you directly to the first program.
The six steps
1. First Program
Run one complete expression in the Playground, save it as a .lspx file, and
learn how a diagnostic points back to where the unfinished form begins.
2. Values, Names, and Procedures
Read literals, bind names with define and let, and create a reusable
procedure. This lesson turns nested parentheses into a predictable evaluation
order.
3. Code Is Data
See why a quoted list and a call share the same shape. Learn why an answer that stays shaped like data is useful in ordinary code.
4. Data, Conditions, and Decisions
Preserve symbols and lists as data, choose with if and cond, and remember
that only #f is false. You will return a labelled decision instead of an
unexplained boolean.
5. First Decision Rule
Combine the earlier pieces into a refund-window rule. Test day 14, day 15, and an opened item so the boundary is visible rather than assumed.
Build the first decision rule →
6. Where Your Program Runs
Name the engine that has been running everything so far, meet the other three, and see why a missing route stops the run instead of quietly switching to another one.
Keep this map beside the course
Syntax at a Glance shows literals, calls, bindings, procedures, conditions, quoted data, aggregates, and higher-order procedures on one page. Use it when you recognize a shape but cannot remember its name. The map links into the full manual. It is the last page in the Learn group. Because it is a reference sheet rather than an exercise, nothing on it needs finishing.
After the course
Choose the path that matches your next question.
- Write more Lispex. Continue with Source Text and Reader, then the language guides.
- Ship a local rule. Read Choosing Where to Run and Downloads.
- Make source visual and reversible. Try Lispex Images.
- Authenticate and recheck a decision. Enter the advanced Lispex Vouch overview.
You do not need to read the manual in page-number order after this course. Use the navigation numbers for orientation, then follow the question you actually have.