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Correl Roush
22fb903209
(monad 'state) is synonymous with (transformer 'state 'identity). The monad macro has been updated to reflect that.
43 lines
1.2 KiB
Text
43 lines
1.2 KiB
Text
(defmacro monad (name)
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(case name
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;; Provide the state monad in terms of the state transformer
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(''state `(transformer 'state 'identity))
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(_
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`(list_to_atom (lists:flatten (list "calrissian-"
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(atom_to_list ,name)
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"-monad"))))))
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(defmacro transformer (name inner-monad)
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`(tuple (list_to_atom (lists:flatten (list "calrissian-"
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(atom_to_list ,name)
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"-transformer")))
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(monad ,inner-monad)))
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(defmacro do-m args
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(let ((monad (car args))
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(statements (cdr args)))
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(calrissian-monad:do-transform monad statements)))
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(defmacro >>= (monad m f)
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`(call ,monad '>>= ,m ,f))
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(defmacro >> (monad m1 m2)
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`(call ,monad '>>= ,m1 (lambda (_) , m2)))
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(defmacro return (monad expr)
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`(call ,monad 'return ,expr))
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(defmacro fail (monad expr)
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`(call ,monad 'fail ,expr))
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(defmacro sequence (monad list)
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`(: lists foldr
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(lambda (m acc) (mcons ,monad m acc))
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(return ,monad [])
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,list))
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(defmacro mcons (monad m mlist)
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`(do-m ,monad
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(x <- ,m)
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(rest <- ,mlist)
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(return ,monad (cons x rest))))
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