The hy.contrib.walk module provides a few functions to walk the Hy AST,
and potentially transform it along the way. The main entry point
is (walk), which takes two functions and a form as arguments, and
applies the first (inner) function to each element of the form, building
up a data structure of the same type as the original. Then applies outer
(the second function) to the result.
Two convenience functions are provided: (postwalk) and (prewalk), which
do a depth-first, post/pre-order traversal of the form.
Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
* hy/core/language.hy: Adding a simple `identity` function that returns
the argument supplied to it
* docs/language/core.rst: Updated docs with identity function
Sometimes it is better to start with the false condition, sometimes that
makes the code clearer. For that, the (if-not) macro, which simply
reverses the order of the condition blocks, can be of great use.
Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
In the same vein as defmacro-alias, this implements defn-alias /
defun-alias, which does essentially the same thing as defmacro-alias,
but for functions.
Signed-off-by: Gergely Nagy <algernon@balabit.hu>
* hy/core/language.hy:
-Added a simple coll? function that checks whether the given argument
is an iterable and not a string,
- Also replaced the check in `flatten` by coll?
* tests/native_tests/core.hy: Tests updated for checking coll?
This cleans up a number of doc warnings, including a bad
underline for zero?
While there, added a nil? function to match up with the
new nil is None.
Also un-hid myself from coreteam.
When calling get with more than two arguments, treat the rest as indexes
into the expression from the former. That is, (get foo "bar" "baz")
would translate to foo["bar"]["baz"], and so on.
This fixes#362.
Requested-by: Sean B. Palmer <sean@miscoranda.com>
Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
* hy/contrib/anaphoric.hy: The following anaphoric macros have been
added
`ap-reject` : Opposite of ap-filter, yields the elements when a `pred`
evaluates to false
`ap-dotimes` : Execute body forms (possibly for side-effects) n times
with `it` bound from 0 to n-1
`ap-first` : return the first element that passes predicate
`ap-last` : return the last element that passes predicate
`ap-reduce`: anaphoric form of reduce that allows `acc` and `it` to
create a function that is applied over the list
* docs/contrib/anaphoric.rst: updated docs to reflect these changes
* tests/__init__.py: updated to explicitly include tests for anaphoric
macros
Apply didn't work on method calls (i.e. `(apply .foo [bar]) broke).
This slipped through because there were no tests of this behavior. I noticed
it while trying to merge the `meth` fixes.
Added first iteration of reader macros
Refactored defmacro and defreader
Added test inn hy/tests/lex/test_lex.py
Added new test in hy/tests/native/tests
Added new test in hy/tests/macros.
changed the error given in the dispatch macro and added some handling for missing symbol and invalid characters
Adding to the manual gensym for macros are 2 new
macros, but very literal from the CL in
letoverlambda.
The first is the (with-gensyms ...) macro that
can generate a small set of syms for a macro. Works
something like:
(defmacro adder2 [A B]
(with-gensyms [a b]
`(let [[~a ~A] [~b ~B]]
(+ ~a ~b))))
and ~a and ~b will be replaced with (gensym "a") and
(gensym "b") respectively.
Then the final macro is a new defmacro that will automatically
replace symbols prefaced with "g!" with a new gensym based on the
rest of the symbol. So in this final version of 'nif':
(defmacro/g! nif4 (expr pos zero neg)
`(let [[~g!result ~expr]]
(cond [(pos? ~g!result) ~pos]
[(zero? ~g!result) ~zero]
[(neg? ~g!result) ~neg])))
all uses of ~g!result will be replaced with (gensym "result").
Simple implementation of gensym in Hy.
Returns a new HySymbol.
Usable in macros like:
(defmacro nif [expr pos zero neg]
(let [[g (gensym)]]
`(let [[~g ~expr]]
(cond [(pos? ~g) ~pos]
[(zero? ~g) ~zero]
[(neg? ~g) ~neg]))))
This addresses all the general comments about (gensym), and doesn't
try to implement "auto-gensym" yet. But clearly the macro approach
instead of the pre-processor approach (as described in the
letoverlambda (http://letoverlambda.com/index.cl/guest/chap3.html#sec_5)
is the way to go
Like other lisps, operators `+` and `*` return their identity values
when called with no arguments. Also with a single operand they return
the operand.
This fixes#372
The fancypants Hy award goes to Nick for coming up with the quoted
symbol hack for exports. This broke with foo?, since the export string
needs to be is_foo, but using a quoted string will pick up the change
due to it being a Symbol.
Mad clown love for that, @olasd.
