| author | wenzelm |
| Thu, 19 Jul 2007 23:18:46 +0200 | |
| changeset 23862 | b1861768d8f4 |
| parent 23850 | f1434532a562 |
| child 24421 | acfb2413faa3 |
| permissions | -rw-r--r-- |
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structure Nat = |
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struct |
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datatype nat = Zero_nat | Suc of nat; |
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end; (*struct Nat*) |
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structure Codegen = |
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struct |
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type 'a null = {null : 'a};
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fun null (A_:'a null) = #null A_; |
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fun head B_ (x :: xs) = x |
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| head B_ [] = null B_; |
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22188
a63889770d57
adjusted manual to improved treatment of overloaded constants
haftmann
parents:
21994
diff
changeset
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val null_option : 'a option = NONE; |
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fun null_optiona () = {null = null_option} : ('b option) null;
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val dummy : Nat.nat option = |
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head (null_optiona ()) [SOME (Nat.Suc Nat.Zero_nat), NONE]; |
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end; (*struct Codegen*) |