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RI.md

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Ri syntax

This document reflects current state of implementation. See To do section in main README.md.

Syntax is heavily inspired by Go, but not the same. Differences so far:

  • No support for short variable declaration a := x, do var a = x instead.
  • No int type, use explicit int32 or int64.
  • return statement is either standalone return or with call arguments return (...).
  • No built-in string type, use []char8, []char16, []char32 instead.
  • No + operator for string concatenation.
  • No &^ (bit-clear, AND NOT) operator.
  • Bitwise complement ^x is implemented as ~x.

Differences from C so far:

  • Strings are slices, not pointers.
  • No string zero-termination guarantee.
  • No comma operator.
  • No while statement, use for.
  • No do-while statement, use for.

Types

Integer types:

  • int8
  • uint8
  • int16
  • uint16
  • int32
  • uint32
  • int64
  • uint64

Character types:

  • char8 (alias int8)
  • char16 (alias int16)
  • char32 (alias int32)

Float types:

  • float32
  • float64

Constants

Named constants

  • const a = 1; -- untyped integer constant a.
  • const a int32 = 1; -- int32 (typed) constant a.

Constant literals

  • 1 -- untyped integer constant (defaults to int64)
  • 1.0 -- untyped float constant (defaults to float32)
  • "abc" -- typed []char8 constant
  • true -- typed bool constant
  • false -- typed bool constant
  • nil -- pointer constant

Untyped constant type inference

Untyped constant type inference is implemented for integer and real constants.

var b int32 = 1;

// Constant '1' will be interpreted as 'int32', because of 'b'.
var a int32 = 1 + b;
// Constant '1' will be interpreted as 'int32', because of 'a'.
var a int32 = 1;
// Variable 'a' is assigned type 'int64', 1 is interpreted to 'int64' because of default constant's type (see above).
var a = 1;
// Constants are treated by their default types 'int64'.
var a bool = 1 < 1;

Syntax

Semicolons

Semicolons are currently required with rules similar to C. Will be re-evaluated to see whether they can be removed.

Declarations

function declaration

  • function <name> (arg, arg,...) (arg, arg, ...) {...}

Function arguments

  • <name> <type>

var declaration

  • var <name> <type>
  • var <name> = <expr>

Type inference

If var declaration omits type, then the declaration must be followed with = assignment, and the type is inferred from the right-hand side expression:

var b int32;

// Variable 'a' will be declared as 'int32' because of 'b'.
var a = b;
var a = b + 1;
// Variable 'a' will be declared as 'int64' because '1' will be interpreted by default type of untyped integer constant.
var a = 1;

Statements

Simple statement

  • Variable declaration
  • Expression
  • Assignment

return statement

  • return ...;

To be changed to:

  • return (...)
  • return

if statement

  • if <pre-st>; <condition> { ... }
  • if <condition> { ... }
  • if ... { ... } else { ... }
  • if ... { ... } else if ...

Where:

  • pre-st is simple statement
  • condition is expression

for statement

  • for <pre-st>; <condition>; <post-st> { ... }
  • for <pre-st>; ; <post-st> { ... }
  • for <pre-st>; ; { ... }
  • for ; ; <post-st> { ... }
  • for ; <condition>; { ... }
  • for ; ; { ... }
  • for <condition> { ... }

Where:

  • pre-st is simple statement
  • post-st is simple statement
  • condition is expression

while with for statement

for condition {
    work();
}

do-while with for statement

for var ok = true; ok; ok = condition {
    work();
}

repeat-until with for statement

for var ok = true; ok; ok = !condition {
    work();
}

Assignment statements

  • a = b
  • a += b
  • a -= b
  • a *= b
  • a /= b
  • a %= b
  • a &= b
  • a |= b
  • a ^= b

Expressions

Call

  • <name>(...)

Arithmetic operators

  • a + b
  • a - b
  • a * b
  • a / b
  • a % b

Bitwise operators

  • ~n
  • a & b
  • a | b
  • a ^ b
  • a << b
  • a >> b

Comparison operators

  • a == b
  • a != b
  • a < b
  • a <= b
  • a > b
  • a >= b

Boolean operators

  • !a
  • a && b
  • a || b