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Refactor for loop to use cond

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Matthew Wampler-Doty 2014-04-22 16:47:42 -07:00
parent 92a1f17b36
commit f2f38a1cf8
1 changed files with 20 additions and 25 deletions
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45
hy/core/macros.hy
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@ -31,31 +31,6 @@
[hy._compat [PY33 PY34]]) [hy._compat [PY33 PY34]])
(defmacro for [args &rest body]
"shorthand for nested for loops:
(for [x foo
y bar]
baz) ->
(for* [x foo]
(for* [y bar]
baz))"
(if (odd? (len args))
(macro-error args "`for' requires an even number of args."))
(if (empty? body)
(macro-error None "`for' requires a body to evaluate"))
(if (empty? args)
`(do ~@body)
(if (= (len args) 2)
; basecase, let's just slip right in.
`(for* [~@args] ~@body)
; otherwise, let's do some legit handling.
(let [[alist (slice args 0 nil 2)]]
`(for* [(, ~@alist) (genexpr (, ~@alist) [~@args])] ~@body)))))
(defmacro with [args &rest body] (defmacro with [args &rest body]
"shorthand for nested for* loops: "shorthand for nested for* loops:
(with [[x foo] [y bar]] baz) -> (with [[x foo] [y bar]] baz) ->
@ -113,6 +88,26 @@
root) root)
(defmacro for [args &rest body]
"shorthand for nested for loops:
(for [x foo
y bar]
baz) ->
(for* [x foo]
(for* [y bar]
baz))"
(cond
[(odd? (len args))
(macro-error args "`for' requires an even number of args.")]
[(empty? body)
(macro-error None "`for' requires a body to evaluate")]
[(empty? args) `(do ~@body)]
[(= (len args) 2) `(for* [~@args] ~@body)]
[true
(let [[alist (slice args 0 nil 2)]]
`(for* [(, ~@alist) (genexpr (, ~@alist) [~@args])] ~@body))]))
(defmacro -> [head &rest rest] (defmacro -> [head &rest rest]
;; TODO: fix the docstring by someone who understands this ;; TODO: fix the docstring by someone who understands this
(setv ret head) (setv ret head)