README
T
EvalResult
- ::createMoonBitVM::create
- ::evalMoonBitVM::eval
- ::newMoonBitVM::new
V
add_embedded_fn
V
add_embedded_method
V
add_extern_fn
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code_to_ast
V
eval_result_to_string
V
expr_to_string
V
value_to_json
V
value_to_string

moonbit-eval

MoonBit Eval Package

moonbit

eval

Download zip

Author

oboard

Version

0.8.26

License

Apache-2.0

Repository

github.com/oboard/moonbit-eval

Last updated

5 months ago

Downloads

161

Dependencies

moonbitlang/parser0.2.5
moonbitlang/x0.4.43

#MoonBit Eval

#Demo

🚀 REPL Demo

🚀 Notebook Demo https://moonbit-notebook.oboard.fun/

#Introduction

MoonBit Eval is an interpreter for the MoonBit language.

Built on top of the @moonbitlang/parser library, it provides comprehensive and accurate MoonBit syntax support, capable of correctly parsing and executing complex MoonBit code structures including functions, structs, lambdas, loops, and more.

#Quick Start

let vm = MoonBitVM::new()

// Basic expressions
inspect(vm.eval("1 + 2 * 3"), content="7")
inspect(vm.eval("\"hello\" + \" world\""), content="hello world")

// Variables and functions
inspect(vm.eval("let x = 42"), content="()")
inspect(vm.eval("fn double(n: Int) -> Int { n * 2 }"), content="(n: Int) -> Int")
inspect(vm.eval("double(x)"), content="84")

// Control flow
inspect(vm.eval("if x > 40 { \"big\" } else { \"small\" }"), content="big")

// Pattern matching
inspect(vm.eval("match (1, 2) { (a, b) => a + b }"), content="3")

// Using aliases (new parser style)
inspect(vm.eval("using @int {abs}", top=true), content="()")
inspect(vm.eval("abs(-5)"), content="5")

#Parser Notes

parse_code_to_expr now uses the same path as moonbitlang/parser handrolled parser tests: lexer.tokens_from_string(...).tokens -> handrolled_parser.parse_expr(...).
This removes the old wrapper trick (fn init { ... }) and keeps expression parsing behavior aligned with upstream.
Diagnostics from parser reports are preserved and returned in Err(...) when parse fails.

#✨ Features

✅ 🥮 Mooncakes Loader: Load Mooncakes packages at runtime
✅ Builtin FileSystem Library: Provides basic file system operations.
✅ Eval Function: Allows dynamic evaluation of MoonBit code strings.

#MoonBit Language Support

Feature	Status	Description
Core Language
Basic Types (Int, Bool, String, Double, Char)	✅	Full support for primitive types
Expressions (arithmetic, logical, comparison)	✅	Complete expression evaluation
Variables (let, let mut)	✅	Immutable and mutable variables
Assignment	✅	Variable reassignment and shadowing
Multiline strings	✅	#\|syntax for multiline string literals
String interpolation	✅	{variable} syntax in string literals
Type constraints	✅	(value : Type) syntax for explicit typing
Control Flow
If-else	✅	Conditional expressions
For loops	✅	C-style for loops with continue/break
While loops	✅	While loop constructs with else clause
Loop control	✅	Continue and break statements
Guard expressions	✅	guard condition else { action } syntax
Is expressions	✅	Pattern matching with 'is' operator
Defer expressions	✅	defer statement for cleanup code
Return expressions	✅	Early return from functions
Raise expressions	✅	Exception throwing with raise
Try-catch expressions	✅	Exception handling with try-catch
Loop expressions	✅	loop pattern matching with break/continue
Functions
Function definitions	✅	Named functions with parameters
Named parameters	✅	Named and optional parameters
Lambda expressions	✅	Anonymous functions (x => x * 2)
Closures	✅	Proper closure environment capture
Recursive functions	✅	Self-referencing function calls
Currying	✅	Higher-order function composition
External functions	✅	Integration with external calls
Embedded functions	✅	Native function integration
Data Structures
Arrays	✅	Array creation, indexing, assignment
Array methods	✅	length, get, push, pop, contains, slice, concat, join
Array boolean methods	✅	any, all operations
Array spread syntax	✅	[..array1, ..array2] syntax
Array slice operations	✅	arr[start:end], arr[start:], arr[:end] syntax
Array augmented assignment	✅	arr[i] += value, arr[i] *= value syntax
Tuples	✅	Tuple creation, access, destructuring
Structs	✅	Custom data types with methods
Mutable struct fields	✅	Field mutation support
Nested struct references	✅	Reference semantics for nested structures
Record update syntax	✅	{ ..record, field: new_value } syntax
Map literals	✅	{ "key": value } syntax for map creation
Pattern Matching
Basic patterns	✅	Constants, variables, wildcards
Tuple patterns	✅	Destructuring tuples
Array patterns	✅	Array destructuring
Record patterns	✅	Struct field matching
Range patterns	✅	Range expressions (_..<x, 'a'..='z')
Constructor patterns	✅	Constant constructor matching
Or patterns	✅	Multiple pattern alternatives
Nested patterns	✅	Complex nested pattern matching
Enums and Generics
Basic enums	✅	Simple enumeration types
Enums with data	✅	Algebraic data types
Enum pattern matching	✅	Pattern matching on enum variants
Generic types	✅	Generic enums and functions
Generic functions	✅	Polymorphic function definitions
Option Type
Option basics	✅	Some/None construction
Option pattern matching	✅	Pattern matching on Option
Option methods	✅	unwrap, unwrap_or, is_empty, map, filter
Built-in Methods
Bool methods	✅	compare, default
Int methods	✅	Bitwise ops, comparisons, bit manipulation
String methods	✅	length, get, unsafe_get, to_string
Double methods	✅	compare, to_int64
Char methods	✅	compare, to_int
Advanced Features
Type system	✅	Basic type checking and inference
Static method calls	✅	Class::method() syntax
Pipe operator	✅	\|> operator for function chaining
Function aliases	✅	using @pkg {name} alias support
Cross-package method calls	✅	Method calls across different packages
Error handling	✅	Result type error handling
Group expressions	✅	Parenthesized expressions for precedence
For-in loops	✅	Iterator-based loops
Iterator methods	✅	iter, map, filter, reduce, for_each
Nested iteration	✅	Complex nested loop structures
Iterator control flow	✅	break/continue in iterator contexts
Package System
Module imports	✅	@package.function syntax
Cross-package types	✅	Using types from other packages
Built-in packages	✅	@int, @math, @bigint, @cmp, @list support
Package method calling	✅	Method calls across package boundaries
IO and FFI
Print functions	✅	println and print support
Embedded functions	✅	Native function integration via FFI
External function binding	✅	Custom function registration
Sorting and Collections
List sorting	✅	Built-in sort methods for collections
Array sorting	✅	Sorting operations on arrays
Collection methods	✅	Comprehensive collection manipulation
Comparison Operations
Equality operators	✅	== and != operators
Relational operators	✅	, <=, >= operators
Type-aware comparison	✅	Proper type checking in comparisons
Constructor Patterns
Single argument matching	✅	Constructor pattern with single args
Named field matching	✅	Constructor patterns with named fields
Wildcard patterns	✅	_ patterns in constructor matching
Functional Programming
Higher-order functions	✅	Functions as first-class values
Function composition	✅	Combining functions effectively
Closure environments	✅	Proper variable capture in closures
Literal Overloading
Numeric literal overloading	✅	Automatic conversion between numeric types
Character literal overloading	✅	Char to Int conversion in pattern matching
String literal overloading	✅	String to Bytes conversion
Array literal overloading	✅	Array to various types (Bytes, String) conversion
Double literal overloading	✅	Double to Float precision conversion
Map literal overloading	✅	Map to Json object conversion
Complex overloading scenarios	✅	Multi-step type conversions
Traits	🟡	Interface definitions
Trait as expressions	🟡	(value as Trait) syntax for trait casting
Packages	🟡	Module system with @package.function syntax (no trait, trait derive, operator overloading)
Attribute
#alias	✅	Function alias
#external	❌	External function binding
#callsite	❌	Call site information
#skip	❌	Skipping compilation of a function
#cfg	❌	Conditional compilation based on configuration
Not Yet Supported
Async/await	🟡	Limited bridge support via %async.run / %async.suspend (no scheduler/event loop)

#Contributing

We welcome contributions to the MoonBit Eval project! Whether it's bug fixes, feature additions, or documentation improvements, your contributions are valuable.

#Community

Join our community for discussions and support:

QQ Group: 949886784

EvalResult

source

pub enum EvalResult {
  Success(@oboard/moonbit-eval/interpreter/core.RuntimeValue
RuntimeValue, @oboard/moonbit-eval/interpreter/core.ClosureInterpreter
ClosureInterpreter)
  Error(String, @oboard/moonbit-eval/interpreter/core.ClosureInterpreter
ClosureInterpreter)
}

impl Show for EvalResult

MoonBitVM

source

pub(all) struct MoonBitVM {
  interpreter : @oboard/moonbit-eval/interpreter/core.ClosureInterpreter
ClosureInterpreter
  log : Bool
}

MoonBitVM::create

source

fn MoonBitVM::create(log? : Bool) -> MoonBitVM

MoonBitVM::eval

source

fn MoonBitVM::eval(self : MoonBitVM, code : String, log? : Bool, top? : Bool) -> EvalResult

MoonBitVM::new

source

fn MoonBitVM::new(log? : Bool) -> MoonBitVM

add_embedded_fn

source

fn add_embedded_fn(vm : MoonBitVM, name : String, func : (@oboard/moonbit-eval/interpreter/core.RuntimeFunctionContext
RuntimeFunctionContext) -> @oboard/moonbit-eval/interpreter/core.RuntimeValue
RuntimeValue raise @oboard/moonbit-eval/interpreter/core.ControlFlow
ControlFlow) -> Unit

add_embedded_method

source

fn add_embedded_method(vm : MoonBitVM, name : String, method_name : String, func : (@oboard/moonbit-eval/interpreter/core.RuntimeFunctionContext
RuntimeFunctionContext) -> @oboard/moonbit-eval/interpreter/core.RuntimeValue
RuntimeValue raise @oboard/moonbit-eval/interpreter/core.ControlFlow
ControlFlow) -> Unit

add_extern_fn

source

fn add_extern_fn(vm : MoonBitVM, name : String, func : (@oboard/moonbit-eval/interpreter/core.RuntimeFunctionContext
RuntimeFunctionContext) -> @oboard/moonbit-eval/interpreter/core.RuntimeValue
RuntimeValue raise @oboard/moonbit-eval/interpreter/core.ControlFlow
ControlFlow) -> Unit

code_to_ast

source

fn code_to_ast(code : String) -> String

eval_result_to_string

source

fn eval_result_to_string(result : EvalResult) -> String

expr_to_string

source

fn expr_to_string(expr : @moonbitlang/parser/syntax.Expr
Expr) -> String

value_to_json

source

fn value_to_json(value : @oboard/moonbit-eval/interpreter/core.RuntimeValue
RuntimeValue) -> String

value_to_string

source

fn value_to_string(value : @oboard/moonbit-eval/interpreter/core.RuntimeValue
RuntimeValue) -> String

Source Files

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moonbit-eval

#MoonBit Eval

#Demo

#Introduction

#Quick Start

#Parser Notes

#✨ Features

#MoonBit Language Support

#Contributing

#Community

#EvalResult

#MoonBitVM

#MoonBitVM::create

#MoonBitVM::eval

#MoonBitVM::new

#add_embedded_fn

#add_embedded_method

#add_extern_fn

#code_to_ast

#eval_result_to_string

#expr_to_string

#value_to_json

#value_to_string

Source Files

EvalResult

MoonBitVM

MoonBitVM::create

MoonBitVM::eval

MoonBitVM::new

add_embedded_fn

add_embedded_method

add_extern_fn

code_to_ast

eval_result_to_string

expr_to_string

value_to_json

value_to_string