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1 Exercise = Main + |
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2 datatype ifex = CIF bool | VIF nat | IF ifex ifex ifex |
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3 consts valif :: ifex => (nat => bool) => bool |
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4 primrec valif ifex |
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5 "valif (CIF b) env = b" |
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6 "valif (VIF x) env = env x" |
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7 "valif (IF b t e) env = (if valif b env then valif t env |
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8 else valif e env)" |
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9 consts normif :: ifex => ifex => ifex => ifex |
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10 primrec normif ifex |
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11 "normif (CIF b) t e = (if b then t else e)" |
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12 "normif (VIF x) t e = IF (VIF x) t e" |
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13 "normif (IF b t e) u f = normif b (normif t u f) (normif e u f)" |
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14 consts norm :: ifex => ifex |
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15 primrec norm ifex |
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16 "norm (CIF b) = CIF b" |
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17 "norm (VIF x) = VIF x" |
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18 "norm (IF b t e) = normif b (norm t) (norm e)" |
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19 consts normal :: ifex => bool |
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20 primrec normal ifex |
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21 "normal(CIF b) = True" |
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22 "normal(VIF x) = True" |
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23 "normal(IF b t e) = (normal t & normal e & |
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24 (case b of CIF b => False | VIF x => True | IF x y z => False))" |
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25 end |