meson.build(5)

✨ NAME ✨

okay bestie, gather round, because we're reading the meson.build(5) page from the File Formats Manual 💖 — this is the whole tea on meson.build, aka a build system dsl 💅

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🦋 DESCRIPTION 🦋

so the meson dsl is a dynamically typed language, lowkey like other interpreted languages such as python and ruby 🐍💎

• every single object is immutable — no cap, you literally cannot mutate anything 👑
• you cannot define functions — only the built-in functions are available, periodt 🙅‍♀️

here's the little map of what's coming up, iykyk:

• STRUCTURE — overview of source and project layout 🗂️
• TYPES — information on all primitive types 🌈
• SYNTAX — description of syntax and keywords ✍️

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🎀 STRUCTURE 🎀

every meson project must have a file called meson.build at the project root 🫶 that's the root build file, bestie. and it must have a call to the project() function as its first statement — first, like, no skipping the line 💀

you can also have extra meson.build files chilling in any subdirectories of the project 🌸 those build files get executed with the subdir() function. iconic behaviour honestly.

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💜 TYPES 💜

the meson build system dsl has most of the common types you'd expect, no surprises here:

• booleans (written as true and false) ✅
• integers 🔢
• strings 🧵
• arrays 📚
• dictionaries 📖

💖 Booleans 💖

booleans are either true or false. that's it, that's the whole vibe 🦋

OPERATORS

• and — logical and
• or — logical or
• not — logical and

🔥 Integers 🔥

you can specify an integer literal using decimal, hexadecimal, octal, and binary — so many flavours, so many options 🍓

int_1 = 1
int_42 = 42
int_255 = 0xFF
int_493 = 0o755
int_1365 = 0b10101010101

all the common arithmetic operations are implemented for integers: addition, subtraction, division, multiplication, and modulo. the whole squad is here 💅

OPERATORS

• * — multiplication
• / — integer division
• % — modulo (remainder)
• + — addition
• - — subtraction
• == — equal to
• != — not equal to
• < — less than
• > — greater than
• <= — less than or equal to
• >= — greater than or equal to

🌸 Strings 🌸

strings in Meson are declared with single quotes ✨ and the backslash (\) is the escape character.

the full list of escape sequences is, and yes you're getting all of them:

• \\ — Backslash
• \' — Single quote
• \a — Bell
• \b — Backspace
• \f — Formfeed
• \n — Newline
• \r — Carriage Return
• \t — Horizontal Tab
• \v — Vertical Tab
• \ooo — Character with octal value ooo, up to 3 digits long
• \xhh — Character with hex value hh
• \uxxxx — Character with 16-bit hex value xxxx
• \Uxxxxxxxx — Character with 32-bit hex value xxxxxxxx
• \N{name} — Character named name in Unicode database

Multi-line strings are surrounded by 3 consecutive quotes 💅 these are raw strings, which means they do not support any of the escape sequences listed above. not one. so don't come crying to me about your \n 😭

Format strings are expressed by placing a leading f before the first opening quote 🧚 inside of a format string, sequences of the form @[a-z_]+@ will be substituted with the value of the matching variable. that variable can be of type bool, int, or str.

name = 'Alice'

# prints "Hello Alice"
message(f'Hello @name@')

OPERATORS

• + — concatenate two strings
• / — concatenate two strings as if join_paths() was called
• [int] — access the character at index
• <str> in <str> — check if str is a substring
• <str> not in <str> — check if str is not a substring
• == — equal to
• != — not equal to

📚 Arrays 📚

arrays are delimited by brackets. an array can contain an arbitrary number of objects of any type — go feral, bestie 🎉

OPERATORS

• + — if the rhs operand is an array, it will be joined to the lhs array. if it is a scalar, it will be appended to the lhs array.
• [int] — access the object at index
• <any> in <array> — check if object is in array
• <any> not in <array> — check if object is not in array
• == — equal to
• != — not equal to

📖 Dictionaries 📖

dictionaries are delimited by curly braces. a dictionary can contain an arbitrary number of key: value pairs 🫶 keys are required to be strings, but values can be objects of any type. dictionaries are immutable and do not have a guaranteed order — so don't you dare rely on ordering, that's giving chaos 🌪️

OPERATORS

• + — merge two dictionaries. in case of a conflicting key, the value from the rhs dictionary will be taken.
• [str] — access the object with key key
• <str> in <dict> — check if key is in dict
• <str> not in <dict> — check if key is not in dict
• == — equal to
• != — not equal to

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🌈 SYNTAX 🌈

a meson build file is composed of statements, which are terminated by newlines ✍️ other than the statement-terminating newline, white space has no syntactic meaning. so go ahead and format it however, it's not that deep 💅

🎀 Comments 🎀

a comment starts with the # character and extends until the end of the line. classic 💬

🦋 Variables 🦋

a variable can contain a value of any type, and does not need to be predeclared 🫶

var1 = 'hello'
var2 = 102

one important difference in how variables work in the dsl is that all objects are immutable 👑 when you see an operation which appears like a mutation, actually a new object is created and assigned to the name. it's giving "new me, who dis" 😌

var1 = [1, 2, 3]
var2 = var1
var2 += [4]
# var2 is now [1, 2, 3, 4]
# var1 is still [1, 2, 3]

💜 Function and method calls 💜

builtin functions are called by their name followed by parenthesis containing optional, comma-separated arguments 🌸 arguments are either positional or keyword. keyword arguments are expressed using the keyword without quotes, followed by a colon.

foo()
foo('bar')
foo('bar', baz: true)

method calls are expressed by a . followed by the same function call syntax as above ✨

foo.bar()
foo.bar('baz', qux: false)

for a complete list of functions and methods, please see meson-reference(3) 📖

🔥 If statements 🔥

start an if statement with the if keyword followed by a boolean expression. further conditions can be expressed using the elif keyword followed by a boolean expression. the else keyword can be used to handle the case when no conditions are matched. an if statement is terminated with the endif keyword ✅

if conditon1
     ...
elif condition2
     ...
else condition3
     ...
endif

🧚 Foreach statements 🧚

to loop over values in an iterable, use the foreach keyword followed by a comma separated list of names to assign the values of the iterable to, a colon, and an iterable expression 🌈 only arrays and dictionaries are iterable. a foreach statement is terminated with the endforeach keyword.

arrays have one value to assign to.

foreach value : array
     foo(value)
endforeach

dictionaries have one two values to assign to.

foreach key, value : dictionary
     foo(key)
     bar(value)
endforeach

inside a foreach block you may use the break and continue keywords 💅 break exits the loop immediately. continue skips the rest of the current iteration.

no cap, those two are your besties when you need out early or need to skip ahead 🙈

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👑 SEE ALSO 👑

• meson-reference(3)
• meson(1)
• muon(1)

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and that's the whole page, bestie 🫶 this was meson.build(5) from the File Formats Manual, dated 2026-02-23 ⭐ go forth and build something iconic 💖✨🎀