| author | haftmann |
| Tue, 03 Mar 2009 11:00:51 +0100 | |
| changeset 30209 | 2f4684e2ea95 |
| parent 25182 | doc-src/IsarAdvanced/Codegen/Thy/examples/class.ML@64e3f45dc6f4 |
| permissions | -rw-r--r-- |
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structure Nat = |
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struct |
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datatype nat = Suc of nat | Zero_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 A_ (x :: xs) = x |
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| head A_ [] = null A_; |
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val null_option : 'a option = NONE; |
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fun null_optiona () = {null = null_option} : ('a 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*) |