From 60f32406e8c9712c0689d54a3dd4f8e17d310d52 Mon Sep 17 00:00:00 2001
From: Josh Chen
Date: Mon, 25 May 2020 18:50:59 +0200
Subject: Lists + more reorganizing

---
 spartan/data/List.thy | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

(limited to 'spartan/data/List.thy')

diff --git a/spartan/data/List.thy b/spartan/data/List.thy
index 71a879b..323ef7e 100644
--- a/spartan/data/List.thy
+++ b/spartan/data/List.thy
@@ -3,4 +3,83 @@ imports Spartan
 
 begin
 
+(*TODO: Inductive type and recursive function definitions. The ad-hoc
+  axiomatization below should be subsumed once general inductive types are
+  properly implemented.*)
+
+axiomatization
+  List    :: \<open>o \<Rightarrow> o\<close> and
+  nil     :: \<open>o \<Rightarrow> o\<close> and
+  cons    :: \<open>o \<Rightarrow> o \<Rightarrow> o \<Rightarrow> o\<close> and
+  ListInd :: \<open>o \<Rightarrow> (o \<Rightarrow> o) \<Rightarrow> o \<Rightarrow> (o \<Rightarrow> o \<Rightarrow> o \<Rightarrow> o) \<Rightarrow> o \<Rightarrow> o\<close>
+where
+  ListF: "A: U i \<Longrightarrow> List A: U i" and
+
+  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
+
+  ListE: "\<lbrakk>
+    xs: List A;
+    c\<^sub>0: C (nil A);
+    \<And>x xs c. \<lbrakk>x: A; xs: List A; c: C xs\<rbrakk> \<Longrightarrow> f x xs c: C (cons A x xs);
+    \<And>xs. xs: List A \<Longrightarrow> C xs: U i
+    \<rbrakk> \<Longrightarrow> ListInd A (\<lambda>xs. C xs) c\<^sub>0 (\<lambda>x xs c. f x xs c) xs: C xs" and
+
+  List_comp_nil: "\<lbrakk>
+    c\<^sub>0: C (nil A);
+    \<And>x xs c. \<lbrakk>x: A; xs: List A; c: C xs\<rbrakk> \<Longrightarrow> f x xs c: C (cons A x xs);
+    \<And>xs. xs: List A \<Longrightarrow> C xs: U i
+    \<rbrakk> \<Longrightarrow> ListInd A (\<lambda>xs. C xs) c\<^sub>0 (\<lambda>x xs c. f x xs c) (nil A) \<equiv> c\<^sub>0" and
+
+  List_comp_cons: "\<lbrakk>
+    xs: List A;
+    c\<^sub>0: C (nil A);
+    \<And>x xs c. \<lbrakk>x: A; xs: List A; c: C xs\<rbrakk> \<Longrightarrow> f x xs c: C (cons A x xs);
+    \<And>xs. xs: List A \<Longrightarrow> C xs: U i
+    \<rbrakk> \<Longrightarrow>
+      ListInd A (\<lambda>xs. C xs) c\<^sub>0 (\<lambda>x xs c. f x xs c) (cons A x xs) \<equiv>
+        f x xs (ListInd A (\<lambda>xs. C xs) c\<^sub>0 (\<lambda>x xs c. f x xs c) xs)"
+
+lemmas
+  [intros] = ListF List_nil List_cons and
+  [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>
+
+definition nil_i ("[]")
+  where [implicit]: "[] \<equiv> nil ?"
+
+definition cons_i (infixr "#" 50)
+  where [implicit]: "x # l \<equiv> cons ? x l"
+
+
+section \<open>Standard functions\<close>
+
+definition "tail A \<equiv> \<lambda>xs: List A. ListRec A (List A) (nil A) (\<lambda>x xs _. xs) xs"
+
+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"
+
+definition tail_i ("tail")
+  where [implicit]: "tail xs \<equiv> List.tail ? xs"
+
+definition map_i ("map")
+  where [implicit]: "map \<equiv> List.map ? ?"
+
+Lemma tail_type [typechk]:
+  assumes "A: U i" "xs: List A"
+  shows "tail xs: List A"
+  unfolding tail_def by typechk
+
+Lemma map_type [typechk]:
+  assumes "A: U i" "B: U i" "f: A \<rightarrow> B" "xs: List A"
+  shows "map f xs: List B"
+  unfolding map_def by typechk
+
+
 end
-- 
cgit v1.2.3