1.0a4

Removals

• Python 3.6 is no longer supported.

Other Breaking Changes

• import and require no longer need outer brackets. (import [foo [bar]]) is now (import foo [bar]) and (import [foo :as baz]) is now (import foo :as baz). To import all names from a module, use (import foo *).

• Lots of objects (listed below) have been spun off to a new package called Hyrule, from which you can import or require them. Thus Hy now brings only the hy module and a limited set of core macros into scope automatically.

  • Functions: butlast, coll?, constantly, dec, destructure, distinct, drop-last, end-sequence, flatten, inc, macroexpand-all, parse-args, pformat, postwalk, pp, pprint, prewalk, readable?, recursive?, rest, saferepr, walk
  • Classes: PrettyPrinter, Sequence
  • Macros: #%, #:, ->, ->>, ap-dotimes, ap-each, ap-each-while, ap-filter, ap-first, ap-if, ap-last, ap-map, ap-map-when, ap-reduce, ap-reject, as->, assoc, cfor, comment, defmacro!, defmacro/g!, defmain, defn+, defn/a+, defseq, dict=:, do-n, doto, fn+, fn/a+, ifp, let+, lif, list-n, loop, ncut, of, profile/calls, profile/cpu, seq, setv+, smacrolet, unless, with-gensyms

• Functions that provide first-class Python operators, such as + in constructs like (reduce + xs), are no longer brought into scope automatically. Say (import hy.pyops *) to get them.

• Hy scoping rules more closely follow Python scoping in certain edge cases.

• let is now a core macro with somewhat different semantics. In particular, definition-like core macros (defn, defclass, import) now introduce new names that shadow corresponding let-bound names and persist outside the body of the let.

• The constructors of String and FString now check that the input would be syntactically legal as a literal.

• hy.extra.reserved has been renamed to hy.reserved.

New Features

• hy.repr now supports several more standard types.
• The attribute access macro . now allows method calls. For example, (. x (f a)) is equivalent to (x.f a).
• hy.as-model checks for self-references in its argument.
• New function hy.model_patterns.keepsym.

Bug Fixes

• In comprehension forms other than for, assignments (other than :setv and loop clauses) are now always visible in the surrounding scope.
• match now only evaluates the subject once.
• let will no longer re-evaluate the default arguments of a
  function it's used in.
• hy.repr now properly formats bracket strings.
• The repr and str of string models now include brackets if necessary.
• When standard output can't accommodate Unicode, hy2py now crashes instead of emitting incorrect Python code.
• Fixed a bug with self-requiring files on Windows.
• Improved error messages for illegal uses of finally and else.