walt-syntax

Walt Syntax

Syntax definitions for the Walt, WebAssembly Alternative Syntax.

Syntax

Numbers

• decimals 1, 20, 42
• floating point 1.1
• hex 0xFF

Stings

• character literals 'x'
• words "hello world!"*

*words require a memory to be present in the module

Types

• i32
• i64
• f32
• f64
• u32
• u64

Keywords

Most JavaScript keywords are supported and have similar(when possible) semantics.

• break
• if
• else
• import
• as
• from
• export
• return
• switch
• case
• default
• const
• let
• for
• continue
• do
• while
• function

Native

Abstract Syntax Tree

Syntax nodes are Plain Old JavaScript Objects.

export type NodeType = {
  range: Marker[],
  Type: string,
  type: string | null,
  value: string,
  meta: { [string]: any },
  params: NodeType[],
};

Type is a pre-defined walt-specific string constant. For a full list of these constants, refer to the source. type(lowercase) is the WebAssembly type and must be one of i32 | f32 | i64 | f64 or the literal null value which represents a void value. Note: Any valid string could be the type value but only the 5 supported values above will compile.

params are the children of the node.

meta is used to hold information about the node which is not present in the source program and is either inferred or implied. For example a struct type definition may contain the key value offsets which are used to compile it's property look ups.

Compile-able AST Types

While many different nodes are possible a strict subset of node Type are considered valid by the generator and are compile-able.

  Syntax.Typedef,
  Syntax.Import,
  Syntax.Export,
  Syntax.FunctionDeclaration,
  Syntax.FunctionCall,
  Syntax.IndirectFunctionCall,
  Syntax.Constant,
  Syntax.BinaryExpression,
  Syntax.TernaryExpression,
  Syntax.IfThenElse,
  Syntax.Else,
  Syntax.Select,
  Syntax.Block,
  Syntax.Identifier,
  Syntax.FunctionIdentifier,
  Syntax.FunctionPointer,
  Syntax.ReturnStatement,
  Syntax.Declaration,
  Syntax.ArraySubscript,
  Syntax.Access,
  Syntax.Assignment,
  Syntax.MemoryAssignment,
  Syntax.Loop,
  Syntax.Break,
  Syntax.TypeCast,
  Syntax.Noop,
  Syntax.NativeMethod