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Remove let

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Yes, bizarrely, this does require editing the implementation of `defn` a little. Without the import, HyList isn't in scope. Defining `let` made it visible due to black magic regarding automatic import.
This commit is contained in:
Kodi Arfer 2017-02-04 09:54:39 -08:00
parent 31f3a55a26
commit 2a44928eb7
2 changed files with 5 additions and 13 deletions
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2
NEWS
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@ -1,6 +1,8 @@
Changes from 0.12.1 Changes from 0.12.1
[ Language Changes ] [ Language Changes ]
* `let` has been removed. Python's scoping rules do not make a proper
implementation of it possible. Use `setv` instead.
* xor: If exactly one argument is true, return it * xor: If exactly one argument is true, return it
[ Bug Fixes ] [ Bug Fixes ]

16
hy/core/bootstrap.hy
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@ -41,23 +41,13 @@
(defmacro defn [name lambda-list &rest body] (defmacro defn [name lambda-list &rest body]
"define a function `name` with signature `lambda-list` and body `body`" "define a function `name` with signature `lambda-list` and body `body`"
(if (not (= (type name) HySymbol)) (import hy)
(if (not (= (type name) hy.HySymbol))
(macro-error name "defn takes a name as first argument")) (macro-error name "defn takes a name as first argument"))
(if (not (isinstance lambda-list HyList)) (if (not (isinstance lambda-list hy.HyList))
(macro-error name "defn takes a parameter list as second argument")) (macro-error name "defn takes a parameter list as second argument"))
`(setv ~name (fn ~lambda-list ~@body))) `(setv ~name (fn ~lambda-list ~@body)))
(defmacro let [variables &rest body]
"Execute `body` in the lexical context of `variables`"
(if (not (isinstance variables HyList))
(macro-error variables "let lexical context must be a list"))
(if (= (len variables) 0)
`((fn []
~@body))
`((fn []
(setv ~@variables)
~@body))))
(defmacro if-python2 [python2-form python3-form] (defmacro if-python2 [python2-form python3-form]
"If running on python2, execute python2-form, else, execute python3-form" "If running on python2, execute python2-form, else, execute python3-form"
(import sys) (import sys)