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feat(hott/init/datatypes): add sum.intro_left and sum.intro_right aliases

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Leonardo de Moura 2014-12-19 17:56:44 -08:00
parent ded869b7e0
commit 69191ef9b7
1 changed files with 6 additions and 0 deletions
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6
hott/init/datatypes.hlean
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@ -38,6 +38,12 @@ inductive sum (A B : Type) : Type :=
inl {} : A → sum A B,
inr {} : B → sum A B
definition sum.intro_left [reducible] {A : Type} (B : Type) (a : A) : sum A B :=
sum.inl a
definition sum.intro_right [reducible] (A : Type) {B : Type} (b : B) : sum A B :=
sum.inr b
-- pos_num and num are two auxiliary datatypes used when parsing numerals such as 13, 0, 26.
-- The parser will generate the terms (pos (bit1 (bit1 (bit0 one)))), zero, and (pos (bit0 (bit1 (bit1 one)))).
-- This representation can be coerced in whatever we want (e.g., naturals, integers, reals, etc).