a0a8103804
This suggestion has been discussed at Slack. We have decided to use #"c" as notation because we wanted to allow `'` in the beginning of identifiers like in SML and F*. In particular, we wanted to allow users to use 'a 'b 'c for naming type parameters like in SML. However, nobody used this notation. In the Lean standard library, we are using greek letters for naming type parameters. So, there is no real motivation for the ugly #"c" syntax.
35 lines
778 B
Text
35 lines
778 B
Text
/-
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Copyright (c) 2016 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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-/
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prelude
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import init.data.fin.basic
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open nat
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def char_sz : nat := succ 255
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def char := fin char_sz
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instance : has_sizeof char :=
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⟨fin.sizeof _⟩
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namespace char
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/- We cannot use tactic dec_trivial here because the tactic framework has not been defined yet. -/
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lemma zero_lt_char_sz : 0 < char_sz :=
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zero_lt_succ _
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@[pattern] def of_nat (n : nat) : char :=
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if h : n < char_sz then fin.mk n h else fin.mk 0 zero_lt_char_sz
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def to_nat (c : char) : nat :=
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fin.val c
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end char
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instance : decidable_eq char :=
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have decidable_eq (fin char_sz), from fin.decidable_eq _,
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this
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instance : inhabited char :=
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⟨'A'⟩
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