LZP

Following: https://buildyourownlisp.com/

Documentation

Overview

This LZP programming language is designed for simplicity and flexibility, enabling users to define functions, perform mathematical operations, manipulate strings, and handle errors. The language supports standard Lisp constructs, including S-expressions and Q-expressions, and provides built-in functions for various common tasks.

Usage

Starting an interactive shell

./lzp

Running a file

./lzp ./examples/pi.lzp

Prelude

Lzp had a build in prelude that can be disabled by passing the -n flag. Have a look in the prelude.lzp file to see what is included.

Types

• NUM: Integer numbers (long)
• FLT: Floating-point numbers (double)
• STR: Strings
• SYM: Symbols
• SEXPR: S-expressions
• QEXPR: Q-expressions
• FUN: Functions (both built-in and user-defined)
• ERR: Error messages

Built-in Functions

List/String Manipulation

List

Converts arguments into a Q-expression.

lzp> list 42 {1 b 1.45} list
{42 {1 b 1.45} <list>}

Head

Returns the first element of a Q-expression or string.

lzp> head {+ 3 - 4}
{x}

lzp> head "exmpl"
"e"

Tail

Returns all elements except the first of a Q-expression or string.

lzp> tail {+ 3 - 4}
{3 - 4}

lzp> tail "exmpl"
"xmpl"

Eval

Evaluates a Q-expression as an S-expression.

lzp> eval {+ 1 1}
2

Join

Concatenates Q-expressions or strings.

lzp> join {+ 1} {2 3}
{+ 1 2 3}

lzp> join "test" "ing"
"testing"

Len

Returns the length of a Q-expression or string.

lzp> len {+ 1 2 3}
4

lzp> len "testing"
7

Arithmetic Operations

+ Addition

lzp> + 1 -.5
0.5

- Subtraction

lzp> - 10 .2
9.8

lzp> - 5
-5

* Multiplication

lzp> * 10 2
20

lzp> 10 .5
5

/ Division

lzp> / 10 2
5

lzp> / 0 10
0

% Modulus

lzp> % 13 5
3

** Exponentiation

lzp> ** 2 8
256

lzp> ** 225 .5
15

min Minimum

lzp> min -4 .2 10
-4

max Maximum

lzp> min -4 .2 10
10

Variable Handling

Def

Defines global variables.

lzp> def {x} 123
()

lzp> + x 100
223

= Assign

Assigns values to variables in the current scope.

lzp> def {i} -1
lzp> def {j} -1
lzp> (\ {_} {def {i} 99}) ()
lzp> (\ {_} {= {j} 99}) ()
lzp> i
99
lzp> j
-1

Logical Operations

> Greater than

lzp> > -10 2.1
0

< Less than

lzp> < -10 2.1
1

>= Greater than or equal to

lzp> >= -10 2.1
0

lzp> >= 2 2
1

<= Less than or equal to

lzp> <= -10 2.1
1

lzp> <= 2 2
1

== Equal to

lzp> == 10 10
1

lzp> == 0 12
0

!= Not equal to

lzp> != 10 10
0

lzp> != 0 12
1

if Conditional expressions

lzp> if 1 { "true" } { "false" }
"true"

lzp> if 0 { "true" } { "false" }
"false"

! Logical NOT

lzp> ! 0
1

lzp> ! 5
0

|| Logical OR

lzp> || 0 0
0

lzp> || 0 0 1 0
1

&& Logical AND

lzp> && 1 0
0

lzp> && 1 1 1 1
1

Functions and Evaluation

exit

Exits the program with a given status code.

lzp> exit 1
echo $?
1

state

Prints the current environment state.

lzp> def {x} 213
lzp> state ()
+ = <+>
- = <->
* = <*>
/ = </>
% = <%>
...
x = 213

\ Lambda

Defines lambda functions. The & syntax allows for varible amount of vars as input.

lzp> (\ {a b} {+ a b}) 1 2
3

lzp> def {add} (\ {a b} {+ a b})
lzp> add 1 2
3

lzp> def {temp} (add 1)
lzp> temp 2
3

lzp> def {add} (\ {& l} {eval (join (list +) l)})
lzp> add 4
4
lzp> add 1 2 3 4 5
15

load

Loads and evaluates code from a file.

lzp> load "./examples/pi.lzp"
Calculating...
3.14149265359004
()

read

Parses and evaluates a string as code.

lzp> read "(def {r} 100); comment\n (show \"aaa\")"
aaa
()
lzp> r
100

print

Prints values, can be of any type.

lzp> print add
(\ {& l} {eval (join (list +) l)})

lpz> print +
<+>

lpz> print "string"
"string"

lzp> print "string\ncool"
"string\ncool"

show

Displays strings.

lzp> print "string"
string

lzp> show "string\ncool"
string
cool

error

Returns an error message.

lzp> error "not good"
Error: not good