Slang

Example code

# this is a comment
#| and that is a
	multiline one. |#

const u32 n = 123123   # n: const u32 (unsigned 32 bit)
const i64 m = 10**18   # m: const i64 (signed 64 bit)
const int z = 2**128   # z: const int (signed unsized)
const auto q = 2**256  # q: const int (signed unsized)

char f(str x) {        # f(): char, x: str
    auto c = x[1]      # c: char
    return c           # char
}

auto g(str x) {        # g(): char, x: str
    return x[0]        # char
}

int h(int x) = x+1     # h(): int, x: int

main {
    stdio.println(h(n), \  # comments allowed here too
        f('123asd') + g('32') + 1)      #--> «123124 f»
    stdio.println(q/z/2**96)            #--> «4294967296.0»
}

Tokens

• Keywords
• Identifiers
• Literals
• Operators
• Specials

Token resolution order

1. Special
2. Operator
3. Literal
4. Keyword
5. Identifier

Syntax structures

Note: * after syntax unit means any number of them.

Abstract

• {[<\n | ;>]* <<expr> <\n | ;>>* [<\n | ;>]*} — code
• <<expr> | <code>> — block

Primitive

• <<funccall> | <itemget> | <attrget> | <identifier> | <lambda> | <literal>> — value
• <(<expr>) | <value> | <operator> <expr> | <expr> <operator> <expr>> — expr (f(x+3) is an instance of expr, also f, x+3 and x are exprs too)

Non-final

• [modifier]* <type> — typedef (left-hand type definition)
• [typedef] <identifier> [? | + | * | ** | =<expr>] — argdef (argument definition)

? — if present then argument value, none else.
+ — tuple with at least one argument.
* — tuple with any number of arguments.
** — object with keyword arguments.
= — default value if argument not specified.

• ([<argdef>[, <argdef>]*]) -> <typedef> = <expr> — lambda (lambda function)
• <<expr>[, <expr>]*[, *<expr>] | *<expr>> — callargs
• <<identifier> =|: <expr>[, <identifier> =|: <expr>]*[, **<expr>] | **<expr>> — callkwargs
• <value>\[<expr>\] — itemget
• <value>.<identifier> — attrget

Final (ordered by resolution order)

• <typedef> <identifier>([<argdef>[, <argdef>]*]) <<code> | = <expr>> — funcdef (function definition)
• <exprkeyword> [expr] — keywordexpr (keyword expression)
• <typedef> <identifier> [= <expr>] — vardef (variable definition)
• <identifier> = <expr> — assignment
• <identifier>[, <identifier>]* = <expr> — unpackassignment
• <value>([<callargs> | <callkwargs> | <callargs>, <callkwargs>]) — funccall (function call)
• <expr> — expr evaluation (only in REPL)
• if (<expr>) <block> — conditional
• for (<identifier> in <expr>) <block> — forloop
• while (<expr>) <block> — whileloop
• else <block> — elseclause

Keywords

• return [expr] — return from function

Modifiers

• const — immutable/constant variable

Reserved keywords

• def
• try
• catch
• except
• finally
• raise
• with
• yield
• include
• using
• default

Identifiers

Non-empty sequence of alphanumeric characters plus underscore («_»), not starting with a digit character.

Regex: [^\W\d][\w]*

Data types

• i8, i16, i32, i64, i128 — fixed size integer

• u8, u16, u32, u64, u128 — fixed size unsigned integer

• f8, f16, f32, f64, f128 — fixed size IEEE-754 floating point number

• uf8, uf16, uf32, uf64, uf128 — fixed size unsigned floating point number

• c8, c16, c32, c64, c128 — fixed size complex number

• uc8, uc16, uc32, uc64, uc128 — fixed size unsigned complex number

• int — unsized («big») integer

• uint — unsized unsigned integer

• float — unsized floating point number

• ufloat — unsized unsigned floating point

• complex — unsized complex number

• ucomplex — unsized unsigned complex number

• bool — logical (boolean) value

• byte — single byte

• char — UTF-8 character

• str — UTF-8 string

• void — nothing (or anything...)

• auto — compile-time type deduction based on value

Literals

Note: * after syntax unit here means any number of them, + means at least one.

• <<0<b | o | x>><digit+> | <digit+>.<digit*> | <digit*>.<digit+>> — number
• <"<character*>" | '<character*>'> — string

Literal structures

• [ <value>[, <value>]* ] — list
• ( [type] <value>[, [type] <value>]* ) — tuple
• { <<key>: <value>>* } — map

Operators

• <operator> <operand> — unary operators usage
• <operand> <operator> <operand> — binary operators usage
• <operand> <operator>= <operand> — in-place operator usage

Character operators

A set of pre-defined character operators:

• !+-~ — unary charset
• %&*+-/<=>^| — binary charset
• ==, **, //, <<, >> — double-char binary operators

Keyword operators

A set of pre-defined keyword operators:

• not — unary keyword operator
• and, or, xor, is, is not, to — binary keyword operators

Specials

• #, #|, |# — comment specials
• ; — expr separator special
• ->, @., @, ., : — attrget optype specials
• [, ] — itemget specials
• \,?=(){} — other specials charset

Footnotes

All character class checks are performed in current locale.

by Sdore, 2021-22
slang.sdore.me