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Rewrite cond

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This commit is contained in:
Kodi Arfer 2019-08-02 14:46:34 -04:00
parent 88c0f92810
commit 6cced31738
1 changed files with 12 additions and 22 deletions
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34
hy/core/macros.hy
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@ -87,29 +87,19 @@ Shorthand for nested with/a* loops:
The result in the bracket may be omitted, in which case the condition is also The result in the bracket may be omitted, in which case the condition is also
used as the result." used as the result."
(if (empty? branches) (or branches
None (return))
(do
(setv branches (iter branches))
(setv branch (next branches))
(defn check-branch [branch]
"check `cond` branch for validity, return the corresponding `if` expr"
(if (not (= (type branch) HyList))
(macro-error branch "cond branches need to be a list"))
(if (< (len branch) 2)
(do
(setv g (gensym))
`(if (do (setv ~g ~(first branch)) ~g) ~g))
`(if ~(first branch) (do ~@(cut branch 1)))))
(setv root (check-branch branch)) `(if ~@(reduce + (gfor
(setv latest-branch root) branch branches
(if
(for [branch branches] (not (and (is (type branch) hy.HyList) branch))
(setv cur-branch (check-branch branch)) (macro-error branch "each cond branch needs to be a nonempty list")
(.append latest-branch cur-branch) (= (len branch) 1) (do
(setv latest-branch cur-branch)) (setv g (gensym))
root))) [`(do (setv ~g ~(first branch)) ~g) g])
True
[(first branch) `(do ~@(cut branch 1))])))))
(defmacro -> [head &rest args] (defmacro -> [head &rest args]