Makrell¶
Makrell is a family of programming languages implemented in Python. It consists currently of these languages:
MakrellPy, a general-purpose, functional programming language with two-way Python interoperability, metaprogramming support and simple syntax.
MRON (Makrell Object Notation), a lightweight alternative to JSON.
MRML (Makrell Markup Language), a lightweight alternative to XML and HTML.
Makrell Base Format (MBF), a simple data format that forms the basis for both MakrellPy, MRON and MRML.
Quick Start¶
Installation¶
$ pip install makrell
MakrellPy REPL usage¶
$ makrell
> 2 + 3
5
> [2 3 5] | sum
10
Run a MakrellPy script¶
$ makrell myscript.mr
IDE Support¶
MakrellPy is supported by the MakrellPy Language Server, included in the Makrell package. The language server is based on the LSP protocol and can be used with any LSP-compatible editor, such as Visual Studio Code, Sublime Text, Atom, Vim, Emacs etc. A VS Code extension is available here.
MakrellPy¶
Main article: MakrellPy
The following is a quick introduction by example to the MakrellPy language.
# This is a comment.
a = 2 # assignment
b = a + 3 # arithmetic expression
{sum [a b 5]} # function call
[a b 5] | sum # function call by pipe operator
sum \ [a b 5] # function call by reverse pipe operator
{if a < b # conditional expression
"a is less than b"
"a is not less than b"}
{fun add [x y] # function definition
x + y}
add3 = {add 3 _} # partial application
{add3 5} # 8
a = 2 | {+ 3} | {* 5} # operators as functions, evaluates to 25
{match a # pattern matching, user extensible
2
"two"
[_ 3|5]
"list with two elements, second is 3 or 5"
_:str
"a string"
_
"something else"
}
{operator 😐 100 # custom operator with precedence level
$left + $right + 1}
{operator 😵 90
$left - $right}
a = 2 😵 3 😐 5
a | print # -7
{assert a == -7}
b = 2 | {😐 3} # 6
# a macro that evaluates expressions in reverse order
{def macro reveval [ns]
ns = ns | regular | operator_parse
{print "[Compile time] Reversing {ns | len} expressions"e}
[{quote {print "This expression is added to the code"}}]
+ (ns | reversed | list)
}
{print "Starting"}
{reveval
"a is now {a}"e | print
a = a + 3
"a is now {a}"e | print
a = 2
}
{print a} # 5
{print "Done"}
# Output:
# [Compile time] Reversing 4 expressions
# Starting
# This expression is added to the code
# a is now 2
# a is now 5
# 5
# Done
Note:
The syntax is determined by lists and binary expressions.
Return values are implicit, i.e. the last expression in a block is the return value.
Other Features¶
Class definitions
String interpolation
Functional programming
Pattern matchings
Metaprogramming, including macros, custom operators and embedded mini-languages
Python interoperability
MRON¶
Main article: MRON (Makrell Object Notation)
Sample MRON document:
owner "Rena Holm"
last_update "2023-11-30"
books [
{
title "That Time of the Year Again"
year 1963
author "Norton Max"
}
{
title "One for the Team"
year 2024
author "Felicia X"
}
]
The above code corresponds to the following Python dictionary tree:
{
"owner": "Rena Holm",
"last_update": "2023-11-30",
"books": [
{
"title": "That Time of the Year Again",
"year": 1963,
"author": "Norton Max"
},
{
"title": "One for the Team",
"year": 2024,
"author": "Felicia X"
}
]
}
It’s possible to embed MakrellPy code in MRON documents, and vice versa. Example:
a 2
b {$ 3 + 5 }
This will be evaluated to this Python dictionary:
{
"a": 2,
"b": 8
}
MRML¶
Main article: MRML (Makrell Markup Language)
Sample MRML document:
{html
{head
{title A Test}
}
{body
{h1 This is a Test}
{p [style="color: red"] Just some {b bold} text here.}
}
}
The above code corresponds to the following HTML:
<!DOCTYPE html>
<html>
<head>
<title>A Test</title>
</head>
<body>
<h1>This is a Test</h1>
<p style="color: red">Just some <b>bold</b> text here.</p>
</body>
</html>
It’s possible to embed MakrellPy code in MRML documents, and vice versa. Example:
{a [b = {$ [2 3 5 7] | sum}] asd}
This will be evaluated to:
<a b="17">asd</a>
Makrell Base Format¶
Main article: Makrell Base Format (MBF)
The Makrell Base Format is a simple data format that forms the basis for both MakrellPy, MRON and MRML. It is a simple text-based format that is easy to read and write. It is designed to be easy to parse and generate, and to be easy to work with in a text editor.
These element types are supported:
- Identifier: A simple name. Examples:
xY1$Example_Æ23.
- String: A sequence of characters surrounded by double quotes. The backslash character is used to escape double quotes and backslashes. A string may have a suffix that specifies an implementation-specific data type. Examples:
"Hi.""This is a string: \"Hi.\"""2024-02-02"date: a date"12AF"hex: a hexadecimal number
- Number: A numeric value. As with strings, a number may have a suffix that specifies an implementation-specific data type or value. Examples:
422.5e92.5G= 2,500,000,0002pi= 6.283185307179586
- List: A sequence of elements, surrounded by brackets and usually separated by spaces. Lists may be nested. There are three types of lists:
“Round”, e.g.
(2 3 5)“Square”, e.g.
["a" "b" "c"]“Curly”, e.g.
{asd qwe zxc}
- Operator: A symbol consisting of one or more non-alphanumeric characters. Examples:
+==|*<*>
For parsing purposes, the following element types are also defined:
Whitespace: A sequence of space, tab and newline characters.
Comment: A sequence of characters that is ignored by the parser. A line comment starts with a # character and continues to the end of the line, while a block comment starts with /* and ends with */.
Other Token: A sequence of characters that does not match any of the other element types.
In addition, the following element type is defined in the core library:
Binary Expression: An operator with two operands.
License¶
Makrell is developed by Hans-Christian Holm and licensed under the MIT License.
Disclaimer¶
The project is in an early stage of development and is not yet ready for production use.