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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 `("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 `("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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