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Merge pull request #1444 from gilch/xi-tag

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change xi macro to #% tag macro
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Tuukka Turto 2017-10-29 21:34:56 +02:00 committed by GitHub
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4 changed files with 118 additions and 77 deletions
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2
NEWS
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@ -22,6 +22,8 @@ Changes from 0.13.0
* support EDN `#_` syntax to discard the next term
* `return` has been implemented as a special form
* `while` loops may now contain an `else` clause, like `for` loops
* `xi` from `hy.extra.anaphoric` is now the `#%` tag macro
* `#%` works on any expression and has a new `&kwargs` parameter `%**`
[ Bug Fixes ]
* Numeric literals are no longer parsed as symbols when followed by a dot

36
docs/extra/anaphoric.rst
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@ -229,21 +229,37 @@ Returns a function which applies several forms in series from left to right. The
=> (op 2)
9
.. _xi
.. _#%
xi
#%
==
Usage ``(xi body ...)``
Usage ``#% expr``
Returns a function with parameters implicitly determined by the presence in the body of xi parameters. An xi symbol designates the ith parameter (1-based, e.g. x1, x2, x3, etc.), or all remaining parameters for xi itself. This is not a replacement for fn. The xi forms cannot be nested.
Makes an expression into a function with an implicit ``%`` parameter list.
This is similar to Clojure's anonymous function literals (``#()``).
A ``%i`` symbol designates the (1-based) *i* th parameter (such as ``%3``).
Only the maximum ``%i`` determines the number of ``%i`` parameters--the
others need not appear in the expression.
``%*`` and ``%**`` name the ``&rest`` and ``&kwargs`` parameters, respectively.
.. code-block:: hy
=> ((xi identity [x1 x5 [x2 x3] xi x4]) 1 2 3 4 5 6 7 8)
[1, 5, [2, 3,] (6, 7, 8), 4]
=> (def add-10 (xi + 10 x1))
=> (add-10 6)
16
=> (#%[%1 %6 42 [%2 %3] %* %4] 1 2 3 4 555 6 7 8)
[1, 6, 42, [2, 3], (7, 8), 4]
=> (#% %** :foo 2)
{"foo": 2}
When used on an s-expression,
``#%`` is similar to Clojure's anonymous function literals--``#()``.
.. code-block:: hy
=> (setv add-10 #%(+ 10 %1))
=> (add-10 6)
16
``#%`` determines the parameter list by the presence of a ``%*`` or ``%**``
symbol and by the maximum ``%i`` symbol found *anywhere* in the expression,
so nesting of ``#%`` forms is not recommended.

91
hy/extra/anaphoric.hy
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@ -5,11 +5,10 @@
;;; These macros make writing functional programs more concise
(defmacro ap-if [test-form then-form &optional else-form]
`(do
(setv it ~test-form)
(if it ~then-form ~else-form)))
(setv it ~test-form)
(if it ~then-form ~else-form)))
(defmacro ap-each [lst &rest body]
@ -25,17 +24,17 @@
(defn ~p [it] ~form)
(for [it ~lst]
(if (~p it)
~@body
(break)))))
~@body
(break)))))
(defmacro ap-map [form lst]
"Yield elements evaluated in the form for each element in the list."
(setv v (gensym 'v) f (gensym 'f))
`((fn []
(defn ~f [it] ~form)
(for [~v ~lst]
(yield (~f ~v))))))
(defn ~f [it] ~form)
(for [~v ~lst]
(yield (~f ~v))))))
(defmacro ap-map-when [predfn rep lst]
@ -43,21 +42,21 @@
predicate function returns True."
(setv f (gensym))
`((fn []
(defn ~f [it] ~rep)
(for [it ~lst]
(if (~predfn it)
(yield (~f it))
(yield it))))))
(defn ~f [it] ~rep)
(for [it ~lst]
(if (~predfn it)
(yield (~f it))
(yield it))))))
(defmacro ap-filter [form lst]
"Yield elements returned when the predicate form evaluates to True."
(setv pred (gensym))
`((fn []
(defn ~pred [it] ~form)
(for [val ~lst]
(if (~pred val)
(yield val))))))
(defn ~pred [it] ~form)
(for [val ~lst]
(if (~pred val)
(yield val))))))
(defmacro ap-reject [form lst]
@ -95,10 +94,10 @@
(defmacro ap-reduce [form lst &optional [initial-value None]]
"Anaphoric form of reduce, `acc' and `it' can be used for a form"
`(do
(setv acc ~(if (none? initial-value) `(get ~lst 0) initial-value))
(ap-each ~(if (none? initial-value) `(cut ~lst 1) lst)
(setv acc ~form))
acc))
(setv acc ~(if (none? initial-value) `(get ~lst 0) initial-value))
(ap-each ~(if (none? initial-value) `(cut ~lst 1) lst)
(setv acc ~form))
acc))
(defmacro ap-pipe [var &rest forms]
@ -112,26 +111,32 @@
"Returns a function which is the composition of several forms."
`(fn [var] (ap-pipe var ~@forms)))
(defmacro xi [&rest body]
"Returns a function with parameters implicitly determined by the presence in
the body of xi parameters. An xi symbol designates the ith parameter
(1-based, e.g. x1, x2, x3, etc.), or all remaining parameters for xi itself.
This is not a replacement for fn. The xi forms cannot be nested. "
(setv flatbody (flatten body))
`(fn [;; generate all xi symbols up to the maximum found in body
~@(genexpr (HySymbol (+ "x"
(str i)))
[i (range 1
;; find the maximum xi
(inc (max (+ (list-comp (int (cut a 1))
[a flatbody]
(and (symbol? a)
(.startswith a 'x)
(.isdigit (cut a 1))))
[0]))))])
;; generate the &rest parameter only if 'xi is present in body
~@(if (in 'xi flatbody)
'(&rest xi)
'())]
(~@body)))
(deftag % [expr]
"Makes an expression into a function with an implicit `%` parameter list.
A `%i` symbol designates the (1-based) ith parameter (such as `%3`).
Only the maximum `%i` determines the number of `%i` parameters--the
others need not appear in the expression.
`%*` and `%**` name the `&rest` and `&kwargs` parameters, respectively.
Nesting of `#%` forms is not recommended."
(setv %symbols (set-comp a
[a (flatten [expr])]
(and (symbol? a)
(.startswith a '%))))
`(fn [;; generate all %i symbols up to the maximum found in expr
~@(genexpr (HySymbol (+ "%" (str i)))
[i (range 1 (-> (list-comp (int (cut a 1))
[a %symbols]
(.isdigit (cut a 1)))
(or (, 0))
max
inc))])
;; generate the &rest parameter only if '%* is present in expr
~@(if (in '%* %symbols)
'(&rest %*))
;; similarly for &kwargs and %**
~@(if (in '%** %symbols)
'(&kwargs %**))]
~expr))

66
tests/native_tests/extra/anaphoric.hy
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@ -65,9 +65,9 @@
(defn test-ap-dotimes []
"NATIVE: testing anaphoric dotimes"
(assert-equal (do (setv n []) (ap-dotimes 3 (.append n 3)) n)
[3 3 3])
[3 3 3])
(assert-equal (do (setv n []) (ap-dotimes 3 (.append n it)) n)
[0 1 2]))
[0 1 2]))
(defn test-ap-first []
"NATIVE: testing anaphoric first"
@ -86,41 +86,59 @@
(assert-equal (ap-reduce (* acc it) [1 2 3]) 6)
(assert-equal (ap-reduce (* acc it) [1 2 3] 6) 36)
(assert-equal (ap-reduce (+ acc " on " it) ["Hy" "meth"])
"Hy on meth")
"Hy on meth")
(assert-equal (ap-reduce (+ acc it) [] 1) 1))
(defn test-ap-pipe []
"NATIVE: testing anaphoric pipe"
(assert-equal (ap-pipe 2 (+ it 1) (* it 3)) 9)
(assert-equal (ap-pipe [4 5 6 7] (list (rest it)) (len it)) 3))
(defn test-ap-compose []
"NATIVE: testing anaphoric compose"
"NATIVE: testing anaphoric compose"
(assert-equal ((ap-compose (+ it 1) (* it 3)) 2) 9)
(assert-equal ((ap-compose (list (rest it)) (len it)) [4 5 6 7]) 3))
(defn test-xi []
"NATIVE: testing xi forms"
(defn test-tag-fn []
"NATIVE: testing #%() forms"
;; test ordering
(assert-equal ((xi / x1 x2) 2 4) 0.5)
(assert-equal ((xi / x2 x1) 2 4) 2)
(assert-equal ((xi identity (, x5 x4 x3 x2 x1)) 1 2 3 4 5) (, 5 4 3 2 1))
(assert-equal ((xi identity (, x1 x2 x3 x4 x5)) 1 2 3 4 5) (, 1 2 3 4 5))
(assert-equal ((xi identity (, x1 x5 x2 x3 x4)) 1 2 3 4 5) (, 1 5 2 3 4))
(assert-equal (#%(/ %1 %2) 2 4) 0.5)
(assert-equal (#%(/ %2 %1) 2 4) 2)
(assert-equal (#%(identity (, %5 %4 %3 %2 %1)) 1 2 3 4 5) (, 5 4 3 2 1))
(assert-equal (#%(identity (, %1 %2 %3 %4 %5)) 1 2 3 4 5) (, 1 2 3 4 5))
(assert-equal (#%(identity (, %1 %5 %2 %3 %4)) 1 2 3 4 5) (, 1 5 2 3 4))
;; test &rest
(assert-equal ((xi sum xi) 1 2 3) 6)
(assert-equal ((xi identity (, x1 xi)) 10 1 2 3) (, 10 (, 1 2 3)))
(assert-equal (#%(sum %*) 1 2 3) 6)
(assert-equal (#%(identity (, %1 %*)) 10 1 2 3) (, 10 (, 1 2 3)))
;; no parameters
(assert-equal ((xi list)) [])
(assert-equal ((xi identity "Hy!")) "Hy!")
(assert-equal ((xi identity "xi")) "xi")
(assert-equal ((xi + "Hy " "world!")) "Hy world!")
(assert-equal (#%(list)) [])
(assert-equal (#%(identity "Hy!")) "Hy!")
(assert-equal (#%(identity "%*")) "%*")
(assert-equal (#%(+ "Hy " "world!")) "Hy world!")
;; test skipped parameters
(assert-equal ((xi identity [x3 x1]) 1 2 3) [3 1])
(assert-equal (#%(identity [%3 %1]) 1 2 3) [3 1])
;; test nesting
(assert-equal ((xi identity [x1 (, x2 [x3] "Hy" [xi])]) 1 2 3 4 5)
(assert-equal (#%(identity [%1 (, %2 [%3] "Hy" [%*])]) 1 2 3 4 5)
[1 (, 2 [3] "Hy" [(, 4 5)])])
;; test arg as function
(assert-equal ((xi x1 2 4) +) 6)
(assert-equal ((xi x1 2 4) -) -2)
(assert-equal ((xi x1 2 4) /) 0.5))
(assert-equal (#%(%1 2 4) +) 6)
(assert-equal (#%(%1 2 4) -) -2)
(assert-equal (#%(%1 2 4) /) 0.5)
;; test &rest &kwargs
(assert-equal (#%(, %* %**) 1 2 :a 'b)
(, (, 1 2)
(dict :a 'b)))
;; test other expression types
(assert-equal (#% %* 1 2 3)
(, 1 2 3))
(assert-equal (#% %** :foo 2)
(dict :foo 2))
(assert-equal (#%[%3 %2 %1] 1 2 3)
[3 2 1])
(assert-equal (#%{%1 %2} 10 100)
{10 100})
(assert-equal (#% #{%3 %2 %1} 1 3 2)
#{3 1 2}) ; sets are not ordered.
(assert-equal (#% "%1")
"%1"))