Welcome to Transcrypt’s documentation!

Can’t find what you’re looking for? The on-line version of this documentation is frequently updated, reflecting the newest features and troubleshooting procedures.

Table of Contents:

• 1. Transcrypt: what and why
  • 1.1. What is Transcrypt
  • 1.2. Language preferences, a subjective account
  • 1.3. The ecosystem: different batteries
  • 1.4. Code structure
  • 1.5. Debuggability
• 2. Getting started
  • 2.1. Installation
    • 2.1.1. Installation troubleshooting checklist
  • 2.2. Your first Transcrypt program
  • 2.3. Available command line switches
  • 2.4. Compiling to JavaScript 6
  • 2.5. Compiling for node.js
  • 2.6. Using sourcemaps and annotated target code
    • 2.6.1. Sourcemaps
    • 2.6.2. Annotated target code
  • 2.7. Static type validation
  • 2.8. Getting help and giving feedback
• 3. Special facilities
  • 3.1. Transcrypt’s module mechanism
  • 3.2. Using browser stubs to test non-GUI code that uses console.log and window.alert
  • 3.3. Creating JavaScript objects with __new__ (<constructor call>)
  • 3.4. The __pragma__ mechanism
    • 3.4.1. The function-like variety
    • 3.4.2. The comment-like variety
    • 3.4.3. The single-line activation variety
    • 3.4.4. The single-line deactivation variety
  • 3.5. Identifier aliasing: __pragma__ (‘alias’, …) and __pragma__ (‘noalias’, …)
  • 3.6. Generating __doc__ attributes from docstrings: __pragma__ (‘docat’) and __pragma__ (‘nodocat’)
  • 3.7. Skipping Transcrypt code fragments when running with CPython: __pragma__ (‘ecom’) and __pragma__ (‘noecom’)
  • 3.8. Surpassing the speed of native JavaScript: __pragma__ (‘fcall’) and __pragma (‘nofcall’)
  • 3.9. Enabling Pythons send syntax: __pragma__ (‘gsend’) and __pragma (‘nogsend’)
  • 3.10. Automatic conversion to iterable: __pragma__ (‘iconv’) and __pragma__ (‘noiconv’)
  • 3.11. Conditional compilation: __pragma__ (‘ifdef’, <symbol>), __pragma__ (‘ifndef’, <symbol>), __pragma__ (‘else’) and __pragma__ (‘endif’)
  • 3.12. Inserting literal JavaScript: __pragma__ (‘js’, …) and __include__ (…)
  • 3.13. Create bare JavaScript objects and iterate over their attributes from Python: __pragma__ (‘jsiter’) and __pragma__ (‘nojsiter’)
  • 3.14. __pragma__ (‘jskeys’) and __pragma__ (‘nojskeys’)
  • 3.15. Keeping your code lean: __pragma__ (‘jsmod’) and __pragma__ (‘nojsmod’)
  • 3.16. __pragma__ (‘keycheck’) and __pragma__ (‘nokeycheck’)
  • 3.17. Keeping your code lean: __pragma__ (‘kwargs’) and __pragma__ (‘nokwargs’)
  • 3.18. Preventing target annotation: __pragma__ (‘noanno’)
  • 3.19. Operator overloading: __pragma__ (‘opov’) and __pragma__ (‘noopov’)
  • 3.20. Skipping fragments while generating code: __pragma__ (‘skip’) and __pragma__ (‘noskip’)
  • 3.21. Automatic conversion to truth value: __pragma__ (‘tconv’) and __pragma__ (‘notconv’)
  • 3.22. Adding directories to the module search path: __pragma__ (‘xpath’, <directory list>)
  • 3.23. Using an external transpiler: __pragma__ (‘xtrans’, <translator>, …, cwd = <workingdirectory>)
• 4. Systematic code examples: a guided tour of Transcrypt
  • 4.1. Arguments: **kwargs, *args, defaults, at call and def time, also for lambda’s
  • 4.2. Attribute access by name: getattr, setattr, hasattr
  • 4.3. Attribute proxies by name: __getattr__, __setattr__
  • 4.4. Bytes and bytearrays: initial support
  • 4.5. Callable or not: using the callable () built-in function
  • 4.6. Classes: multiple inheritance and assignment of bound functions
  • 4.7. Complex numbers: Python’s builtin complex datatype
  • 4.8. Conditional expressions: simple and nested
  • 4.9. Control structures: for…else, while…else, if…elif…else, break, continue
  • 4.10. Data classes: Avoiding boilerplate code
  • 4.11. Data structures: tuple, list, dict, set
  • 4.12. Decorators: function and class, with and without parameters
  • 4.13. Dict comprehensions
  • 4.14. Dictionaries: dict revisited
  • 4.15. Diverse issues
  • 4.16. Diverse pulls
  • 4.17. Docstrings: __doc__ attribute generated optionally
  • 4.18. Exceptions: exception class hierarchy, finally
  • 4.19. Extended slices: facilitating NumScrypt and such
  • 4.20. General functions: sort and sorted
  • 4.21. Global variable access by using globals () [<variable_name>]
  • 4.22. Indices and slices: LHS, RHS, basic and extended
  • 4.23. Iterators and generators
  • 4.24. Lambda functions with all types of args
  • 4.25. List comprehensions: multi-loop and nested with multiple if’s
  • 4.26. Local classes: inside other classes and functions
  • 4.27. Metaclasses: overriding type.__new__ in a descendant metaclass
  • 4.28. Method and class decorators
  • 4.29. Module builtin: a small part of it demo’ed
  • 4.30. Module cmath: almost all of Python’s cmath module
  • 4.31. Module datetime: transcryption of Python’s datetime module
  • 4.32. Module itertools: almost all of Python’s itertools module
  • 4.33. Module math: almost all of Python’s math module
  • 4.34. Module random: most important functions of Python’s random module
  • 4.35. Module re: transcryption of Python’s re module
  • 4.36. Module time: transcryption of Python’s time module
  • 4.37. Modules: hierarchical, both local to the project and global url-based
  • 4.38. Nonlocals
  • 4.39. Operator overloading
  • 4.40. Properties
  • 4.41. Representation as text: the repr and str built-in functions
  • 4.42. Set comprehensions
  • 4.43. Super
  • 4.44. Simple and augmented assignment
  • 4.45. Truthyness: optional Python-style evaluation of truthyness, falsyness and non-empty container selection
  • 4.46. Tuple assignment: recursive and in for-headers using enumerate
• 5. Seamless interoperation with the DOM
  • 5.1. Practical example: a simple, responsive website using no HTML or CSS at all
  • 5.2. SVG example: Turtle graphics
• 6. Mixed examples
  • 6.1. Example: Pong
    • 6.1.1. Three ways of integration with JavaScript libraries
    • 6.1.2. Minification
  • 6.2. Example: jQuery
  • 6.3. Example: iOS web app with native look and feel
  • 6.4. Example: D3.js
  • 6.5. Example: React
  • 6.6. Example: Riot
  • 6.7. Example: Using input and print in a DOM __terminal__ element in your browser
  • 6.8. Example: Using the Parcel.js bundler to package a set of modules written in diverse programming languages
• 7. Autotesting Transcrypt code
  • 7.1. Why it’s needed
  • 7.2. How it works
• 8. The philosophy behind Transcrypt and its impact on design decisions
  • 8.1. Transcrypt’s primary target audience
    • 8.1.1. Seasoned Python developers
    • 8.1.2. Seasoned JavaScript developers
    • 8.1.3. Other developers
  • 8.2. How to best serve this target audience
  • 8.3. Specific design choices made for Transcrypt and their underlying motivation
    • 8.3.1. Why is Transcrypt written in Python and not in JavaScript
    • 8.3.2. Why does Transcrypt blend Python data types with JavaScript data types
    • 8.3.3. Why are certain Python constructions supported as a local (or global) option rather than by default
    • 8.3.4. Why were the __pragma__’s added
• 9. The main differences with CPython
  • 9.1. Differences due to the compiled, rather than interpreted nature of Transcrypt
  • 9.2. Differences due to the ‘lean and mean’ design goal
  • 9.3. Differences due to interoperability with JavaScript and JavaScript libraries
  • 9.4. Differences due to running Transcrypt applications in the browser, rather than on the desktop