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https://github.com/janet-lang/janet
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74 lines
2.0 KiB
Plaintext
74 lines
2.0 KiB
Plaintext
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# Simpler iteration primitives example.
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(defn- iter-for
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[prelude binding start end body]
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(def $end (gensym))
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(tuple 'do
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prelude
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(tuple 'var binding start)
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(tuple 'def $end end)
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(tuple 'while (tuple < binding $end)
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body
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(tuple '++ binding))))
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(defn- iter-keys
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[prelude binding tab body]
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(tuple 'do
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prelude
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(tuple 'var binding (tuple next tab nil))
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(tuple 'while (tuple not= nil binding)
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body
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(tuple := binding (tuple next tab binding)))))
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(defmacro do-range
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"Iterate over a half open integer range."
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[binding start end & body]
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(def $iter (gensym))
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(iter-for nil $iter start end
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(apply tuple 'do (tuple 'def binding $iter) body)))
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(defmacro each
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"Iterate over an indexed data structure."
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[binding ind & body]
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(def $iter (gensym))
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(def $ind (gensym))
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(iter-for (tuple 'def $ind ind)
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$iter 0 (tuple length $ind)
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(apply tuple 'do (tuple 'def binding (tuple get $ind $iter)) body)))
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(defmacro each-key
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"Iterate over keys of a table or structure."
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[binding tab & body]
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(def $tab (gensym))
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(def $key (gensym))
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(iter-keys
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(tuple 'def $tab tab)
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$key
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$tab
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(apply tuple 'do (tuple 'def binding $key) body)))
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(defmacro each-value
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"Iterate over values of a table or structure."
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[binding tab & body]
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(def $tab (gensym))
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(def $key (gensym))
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(iter-keys
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(tuple 'def $tab tab)
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$key
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$tab
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(apply tuple 'do (tuple 'def binding (tuple 'get $tab $key)) body)))
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(defmacro each-pair
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"Iterate over keys and values of a table or structure."
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[k v tab & body]
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(def $tab (gensym))
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(def $key (gensym))
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(iter-keys
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(tuple 'def $tab tab)
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$key
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$tab
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(apply tuple 'do
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(tuple 'def k $key)
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(tuple 'def v (tuple 'get $tab $key)) body)))
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