2015-01-17 23:46:23 +01:00
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==========
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Flow
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==========
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2015-01-18 13:34:07 +01:00
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.. versionadded:: 0.10.1
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2015-01-17 23:46:23 +01:00
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2015-07-24 09:52:33 +02:00
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The ``flow`` macros allow directing the flow of a program with greater ease.
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2015-01-17 23:46:23 +01:00
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Macros
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======
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2015-01-18 13:34:07 +01:00
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.. _case:
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2015-01-17 23:46:23 +01:00
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.. _switch:
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2015-01-18 13:34:07 +01:00
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case
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2015-01-17 23:46:23 +01:00
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-----
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2015-01-18 13:34:07 +01:00
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``case`` allows you to decide based on the value of a variable.
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2015-01-17 23:46:23 +01:00
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2015-01-18 13:34:07 +01:00
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Usage: `(case variable val1 (body1) val2 (body2) ...)`
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2015-01-17 23:46:23 +01:00
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Example:
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.. code-block:: hy
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Give `require` the same features as `import` (#1142)
Give `require` the same features as `import`
You can now do (require foo), (require [foo [a b c]]), (require [foo [*]]), and (require [foo :as bar]). The first and last forms get you macros named foo.a, foo.b, etc. or bar.a, bar.b, etc., respectively. The second form only gets the macros in the list.
Implements #1118 and perhaps partly addresses #277.
N.B. The new meaning of (require foo) will cause all existing code that uses macros to break. Simply replace these forms with (require [foo [*]]) to get your code working again.
There's a bit of a hack involved in the forms (require foo) or (require [foo :as bar]). When you call (foo.a ...) or (bar.a ...), Hy doesn't actually look inside modules. Instead, these (require ...) forms give the macros names that have periods in them, which happens to work fine with the way Hy finds and interprets macro calls.
* Make `require` syntax stricter and add tests
* Update documentation for `require`
* Documentation wording improvements
* Allow :as in `require` name lists
2016-11-03 08:35:58 +01:00
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(require [hy.contrib.flow [case]])
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2015-07-24 09:52:33 +02:00
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(defn temp-commenter [temp]
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(case temp
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-10 (print "It's freezing. Turn up the thermostat!")
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15 (print "Sounds about average.")
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45 (print "Holy smokes. It's hot in here!")
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2015-01-18 13:34:07 +01:00
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(print "I don't even know.")))
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2015-01-17 23:46:23 +01:00
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2015-07-24 09:52:33 +02:00
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2015-01-17 23:46:23 +01:00
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switch
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-----
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``switch`` allows you to run code based on the value of a variable.
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A final extra body allows for a default case.
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Usage: `(switch var (cond1) (body1) (cond2) (body2) ... )`
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Example:
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.. code-block:: hy
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Give `require` the same features as `import` (#1142)
Give `require` the same features as `import`
You can now do (require foo), (require [foo [a b c]]), (require [foo [*]]), and (require [foo :as bar]). The first and last forms get you macros named foo.a, foo.b, etc. or bar.a, bar.b, etc., respectively. The second form only gets the macros in the list.
Implements #1118 and perhaps partly addresses #277.
N.B. The new meaning of (require foo) will cause all existing code that uses macros to break. Simply replace these forms with (require [foo [*]]) to get your code working again.
There's a bit of a hack involved in the forms (require foo) or (require [foo :as bar]). When you call (foo.a ...) or (bar.a ...), Hy doesn't actually look inside modules. Instead, these (require ...) forms give the macros names that have periods in them, which happens to work fine with the way Hy finds and interprets macro calls.
* Make `require` syntax stricter and add tests
* Update documentation for `require`
* Documentation wording improvements
* Allow :as in `require` name lists
2016-11-03 08:35:58 +01:00
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(require [hy.contrib.flow [switch]])
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2015-07-24 09:52:33 +02:00
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(defn temp-commenter [temp]
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(switch temp
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(<= 10.0) (print "Better wear a jacket!")
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(<= 25.0) (print "Brace yourselves. Summer is coming!")
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(<= 30.0) (print "Time to get some ice cream.")
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(print "Sounds like a heat wave")))
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