diff options
author | Josh Chen | 2020-05-26 16:39:35 +0200 |
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committer | Josh Chen | 2020-05-26 16:39:35 +0200 |
commit | 8ba8357a0b4640a3be817fd0645d026b568bc552 (patch) | |
tree | 2deb740dfc97187f5124025b610dc7ef0906a988 /spartan/data/List.thy | |
parent | e6b5a8f3e1128495d9e956fa4f4fa56da02350dc (diff) |
Maybe and more List
Diffstat (limited to '')
-rw-r--r-- | spartan/data/List.thy | 74 |
1 files changed, 67 insertions, 7 deletions
diff --git a/spartan/data/List.thy b/spartan/data/List.thy index a6c41c6..3399da6 100644 --- a/spartan/data/List.thy +++ b/spartan/data/List.thy @@ -1,5 +1,5 @@ theory List -imports Spartan +imports Maybe begin @@ -17,7 +17,7 @@ where List_nil: "A: U i \<Longrightarrow> nil A: List A" and - List_cons: "\<lbrakk>x: A; l: List A\<rbrakk> \<Longrightarrow> cons A x l: List A" and + List_cons: "\<lbrakk>x: A; xs: List A\<rbrakk> \<Longrightarrow> cons A x xs: List A" and ListE: "\<lbrakk> xs: List A; @@ -46,24 +46,78 @@ lemmas [elims "?xs"] = ListE and [comps] = List_comp_nil List_comp_cons -abbreviation "ListRec A C \<equiv> ListInd A (K C)" - - -section \<open>Implicit notation\<close> +abbreviation "ListRec A C \<equiv> ListInd A (\<lambda>_. C)" definition nil_i ("[]") where [implicit]: "[] \<equiv> nil ?" definition cons_i (infixr "#" 50) - where [implicit]: "x # l \<equiv> cons ? x l" + where [implicit]: "x # xs \<equiv> cons ? x xs" + +translations + "[]" \<leftharpoondown> "CONST List.nil A" + "x # xs" \<leftharpoondown> "CONST List.cons A x xs" + + +section \<open>List notation\<close> + +syntax + "_list" :: \<open>args \<Rightarrow> o\<close> ("[_]") +translations + "[x, xs]" \<rightleftharpoons> "x # [xs]" + "[x]" \<rightleftharpoons> "x # []" section \<open>Standard functions\<close> +\<comment> \<open> +definition "head A \<equiv> \<lambda>xs: List A. + ListRec A (Maybe A) (Maybe.none A) (\<lambda>x _ _. Maybe.some A x) xs" +\<close> + +Lemma (derive) head: + assumes "A: U i" "xs: List A" + shows "Maybe A" +proof (elim xs) + show "none: Maybe A" by intro + show "\<And>x. x: A \<Longrightarrow> some x: Maybe A" by intro +qed + +thm head_def \<comment> \<open>head ?A ?xs \<equiv> ListRec ?A (Maybe ?A) none (\<lambda>x xs c. some x) ?xs\<close> + +\<comment> \<open> definition "tail A \<equiv> \<lambda>xs: List A. ListRec A (List A) (nil A) (\<lambda>x xs _. xs) xs" +\<close> + +Lemma (derive) tail: + assumes "A: U i" "xs: List A" + shows "List A" +proof (elim xs) + show "[]: List A" by intro + show "\<And>xs. xs: List A \<Longrightarrow> xs: List A" . +qed +thm tail_def + +\<comment> \<open> definition "map A B \<equiv> \<lambda>f: A \<rightarrow> B. \<lambda>xs: List A. ListRec A (List B) (nil B) (\<lambda>x _ c. cons B (f `x) c) xs" +\<close> + +Lemma (derive) map: + assumes "A: U i" "B: U i" "f: A \<rightarrow> B" "xs: List A" + shows "List B" +proof (elim xs) + show "[]: List B" by intro + next fix x xs ys + assume "x: A" "xs: List A" "ys: List B" + show "f x # ys: List B" by typechk +qed + +thm map_def + +definition head_i ("head") + where [implicit]: "head xs \<equiv> List.head ? xs" definition tail_i ("tail") where [implicit]: "tail xs \<equiv> List.tail ? xs" @@ -72,9 +126,15 @@ definition map_i ("map") where [implicit]: "map \<equiv> List.map ? ?" translations + "head" \<leftharpoondown> "CONST List.head A" "tail" \<leftharpoondown> "CONST List.tail A" "map" \<leftharpoondown> "CONST List.map A B" +Lemma head_type [typechk]: + assumes "A: U i" "xs: List A" + shows "head xs: Maybe A" + unfolding head_def by typechk + Lemma tail_type [typechk]: assumes "A: U i" "xs: List A" shows "tail xs: List A" |