├── .fdignore
├── LICENSE
├── README.md
├── multimethod.janet
├── project.janet
└── test
    └── multimethod.janet


/.fdignore:
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1 | .git
2 | 


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/LICENSE:
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 1 | MIT License
 2 | 
 3 | Copyright (c) 2019 Jon Staab
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


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/README.md:
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1 | # janet-multimethod
2 | 
3 | A multimethod library for Janet
4 | 
5 | # Disclaimer
6 | 
7 | This is pre-alpha software. Please open an issue if you'd like to use it in a project.
8 | 


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/multimethod.janet:
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 1 | # Get-meta is a sentinel value that allows us to return meta
 2 | (def- $get-meta (gensym))
 3 | 
 4 | (defn multimethod
 5 |   [dispatch]
 6 |   (let [methods @{}
 7 |         meta {:dispatch dispatch :methods methods}]
 8 |     (fn [& args]
 9 |       (if
10 |         (= $get-meta (first args))
11 |         meta
12 |         (let [method (or (methods (dispatch ;args)) (methods :default))]
13 |           (if method
14 |             (method ;args)
15 |             (error (string/format "No method found for dispatch values: %q" args))))))))
16 | 
17 | (defmacro defmulti
18 |   [name & opts]
19 |   (let [[docstring dispatch] (if (string? (first opts)) opts [(string name) ;opts])]
20 |     ~(def ,name ,docstring (multimethod ,dispatch))))
21 | 
22 | (defn add-method
23 |   [mm k f]
24 |   (put ((mm $get-meta) :methods) k f))
25 | 
26 | (defmacro defmethod
27 |   [mm k & body]
28 |   ~(add-method ,mm ,k (fn ,;body)))
29 | 


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/project.janet:
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1 | (declare-project
2 |  :name "janet-multimethod"
3 |  :description "A multimethod library for Janet"
4 |  :dependencies ["https://github.com/staab/janet-assert"])
5 | 
6 | (declare-source
7 |   :source ["multimethod.janet"])
8 | 


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/test/multimethod.janet:
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 1 | (use assert)
 2 | (use multimethod)
 3 | 
 4 | (defmulti thing |($ :x))
 5 | 
 6 | (defmethod thing 1 [{:x x}] (inc x))
 7 | (defmethod thing 2 [{:x x}] (dec x))
 8 | 
 9 | (assert= 2 (thing {:x 1}))
10 | (assert= 1 (thing {:x 2}))
11 | 
12 | (defmulti thing "stuff" |($ :x))
13 | 
14 | (defmethod thing 1 [{:x x}] (inc x))
15 | (defmethod thing 2 [{:x x}] (dec x))
16 | 
17 | (assert= 2 (thing {:x 1}))
18 | (assert= 1 (thing {:x 2}))
19 | 


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