simplepy

An interpreter for a subset of the Python language, written purely in Dart. It is intended for adding scripting capabilities to Dart projects and for educational purposes.

Features

  • Available python features:

    • Variable types: int, float, bool, str, list, dict, set, tuple, NoneType
      (some dict methods with limitations)
    • f-strings: {value:[[fill]align][sign][0][width][.precision][dfs]} ; #, and types b/o/x/e/g/% are not yet supported.
    • arithmetic operators: + - * / // ** % and bitwise operators
    • assignments: = += -= *= /= **= //= %=
    • comparisons: == > >= < <= !=
    • boolean operators: and, or, not
    • if, else, elif
    • for loops, while loops
    • try/except/else/finally
    • functions (default arguments, *args, **kwargs are partially implemented), lambda functions
    • some built-in functions: print(), range(), len(), str(), repr(), int(), float(), bool(), type(), list(), dict(), set(), tuple(), abs(), round(), min(), max(), sum(), isinstance()
    • list, dict and set comprehensions
    • list, string and tuple slices - read only
    • classes (no class attributes, no multiple inheritance)
    • global and nonlocal variables

    Some more features might be added soon, but this will never become a full python interpreter.

  • Missing python features:

    • int limited to dart int: ±1<<63 native ; ±1<<53 in web
    • dict.key(), dict.values(), dict.items() return list copies, not dynamic views as in Python
    • set operators | & - ^ <= >= (but available as set1.union(set2)` etc.)
    • :=operator
    • import
    • slice assignments (like x[5:10] = [1,2,3]))
    • file I/O
    • decorators
    • async functions, generators
    • input() and some other built-in functions
    • complex numbers
    • multiple statements in one line separated by ;
    • dunder methods (__xxx__) except for __init__
    • anything else not mentioned as available

Usage

import 'package:simplepy/simplepy.dart';

void main() {
  String py = "print(3**4)";
  final tokens = Lexer(py).scanTokens();
  final stmts = Parser(tokens).parse();
  Interpreter().interpret(stmts);
}

Additional information

Please report any errors (except for missing features, that are not mentioned as available) at the issue tracker.

Libraries

simplepy
simplepy_io