PAL

PAL is an esolang created by islptng.

Programs consist of a single expression containing nested function calls, lambdas and literals (numbers and lists), written using Polish (prefix) notation. Each function has a predefined number of arguments, making the notation unambiguous. This language is tacit.

No description about commands in this esolang should be provided (examples are welcome here).

Data types

There are 3 data types.

• Number, which stores a fraction.
• List, which stores a list of objects.
• Lambda, which is a monadic lambda function

Syntax

In this esolang, a program is a single expression. They're written in Polish(Prefix) notation.

Like @ and XENBLN, expressions are made of trees of function calls. Each character represents a function that takes a predefined amount of arguments, which follow directly after it in the code. For example, if command A takes 1 argument, B takes 2, C takes 3, and D and E both take none, then this code

CBADCDBEDEDAE

would be written in many languages like

C(B(A(D()),C(D(),B(E(),D()),E()))),D(),A(E()))

There are exceptions. To define a list, you use []; To define a lambda, you use {}.

There are some special cases in the console.
A line that begins with ] defines macros.

To separate 2 integers, use a space. Otherwise, you won't need any separators.

True is 1, and False is -1 (unlike most languages, which is 0; In this language, however, 0 is truthy).

Output list structures

It's a bit strange. Let's say you want to evaluate the Loshu:

[[4 9 2][3 5 7][8 1 6]]

> v v v
  4 3 8
  9 5 1
  2 7 6

A > means a list that was displayed horizontally, and a v means a list that was displayed vertically.
Horizontal and vertical takes turn to appear.

Therefore, if you want to display your matrix correctly, you need to either transpose it (recommended):

t[[4 9 2][3 5 7][8 1 6]]

> v v v
  4 9 2
  3 5 7
  8 1 6

Or enclose it:

[[[4 9 2][3 5 7][8 1 6]]]

> v
  > 4 9 2
  > 3 5 7
  > 8 1 6

A more nested example:

[3 7[4 6[2 5 7 4 1]8]5 9 2]

> 3 7 v           5 9 2
      4
      6
      > 2 5 7 4 1
      8

Strings

In this esolang, there are no clear type of strings.
However, strings are representated by a depth-3 array of ASCII values. For example,

[[[72 105 33 10]]]

is actually equivalent to "Hi!\n".

Formatting exist:

[[[72 105 33 10[+1 2]10]]]

Equivalent to python f"Hi!\n{1+2}\n".

Implementation

Try it online!

Examples

Hello World

[[[72 101 108 108 111 44 32 119 111 114 108 100 33 10]]]

XKCD Random Number and Quine

4

Since the whole program is an expression, a single number evaluates to itself, and finally it's printed.

A+B problem

+

Follow it by the 2 numbers you want to input.

Factorial

f{i1\*r1+1x1} 10

Output: 3628800 (10! = 3628800)

FizzBuzz

[~{?=0%x5?=0%x3[[[70 105 122 122 66 117 122 122]]][[[66 117 122 122]]]?=0%x3[[[70 105 122 122]]]x}r1 101 1]

Since this language is not able to print (only evaluation), the result will be a list.