From 2ddafb240afcad5df370ef2850eb8912819657ae Mon Sep 17 00:00:00 2001
From: Sam Caldwell <samc@ccs.neu.edu>
Date: Mon, 29 Apr 2019 18:07:23 -0400
Subject: [PATCH] add sequences

---
 racket/typed/roles.rkt           |  3 ++
 racket/typed/sequence.rkt        | 71 ++++++++++++++++++++++++++++++++
 racket/typed/tests/sequences.rkt | 19 +++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 racket/typed/sequence.rkt
 create mode 100644 racket/typed/tests/sequences.rkt

diff --git a/racket/typed/roles.rkt b/racket/typed/roles.rkt
index dd19f88..061cca3 100644
--- a/racket/typed/roles.rkt
+++ b/racket/typed/roles.rkt
@@ -37,6 +37,8 @@
          (all-from-out "list.rkt")
          ;; sets
          (all-from-out "set.rkt")
+         ;; sequences
+         (all-from-out "sequence.rkt")
          ;; DEBUG and utilities
          print-type print-role
          ;; Extensions
@@ -51,6 +53,7 @@
 (require "list.rkt")
 (require "set.rkt")
 (require "prim.rkt")
+(require "sequence.rkt")
 
 (require (prefix-in syndicate: syndicate/actor-lang))
 
diff --git a/racket/typed/sequence.rkt b/racket/typed/sequence.rkt
new file mode 100644
index 0000000..62ca918
--- /dev/null
+++ b/racket/typed/sequence.rkt
@@ -0,0 +1,71 @@
+#lang turnstile
+
+(provide Sequence
+         (for-syntax ~Sequence)
+         empty-sequence
+         sequence->list
+         sequence-length
+         sequence-ref
+         sequence-tail
+         sequence-append
+         sequence-map
+         sequence-andmap
+         sequence-ormap
+         sequence-fold
+         sequence-count
+         sequence-filter
+         sequence-add-between
+         in-list
+         in-set
+         )
+
+(require "core-types.rkt")
+(require (only-in "list.rkt" List))
+(require (only-in "set.rkt" Set))
+#;(require (postfix-in - racket/sequence))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Sequences
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define-container-type Sequence #:arity = 1)
+
+(require/typed racket/sequence
+  [empty-sequence : (Sequence (U))]
+  [sequence->list : (∀ (X) (→fn (Sequence X) (List X)))]
+  [sequence-length : (∀ (X) (→fn (Sequence X) Int))]
+  [sequence-ref : (∀ (X) (→fn (Sequence X) Int Int))]
+  [sequence-tail : (∀ (X) (→fn (Sequence X) Int (Sequence X)))]
+  [sequence-append : (∀ (X) (→fn (Sequence X) (Sequence X) (Sequence X)))]
+  [sequence-map : (∀ (A B) (→fn (→fn A B) (Sequence A) (Sequence B)))]
+  [sequence-andmap : (∀ (X) (→fn (→fn X Bool) (Sequence X) Bool))]
+  [sequence-ormap : (∀ (X) (→fn (→fn X Bool) (Sequence X) Bool))]
+  ;; sequence-for-each omitted until a better accounting of effects (TODO)
+  [sequence-fold : (∀ (A B) (→fn (→fn A B A) (Sequence B) A))]
+  [sequence-count : (∀ (X) (→fn (→fn X Bool) (Sequence X) Int))]
+  [sequence-filter : (∀ (X) (→fn (→fn X Bool) (Sequence X) (Sequence X)))]
+  [sequence-add-between : (∀ (X) (→fn (Sequence X) X (Sequence X)))])
+
+(require/typed racket/base
+  [in-list : (∀ (X) (→fn (List X) (Sequence X)))])
+(require/typed racket/set
+  [in-set : (∀ (X) (→fn (Set X) (Sequence X)))])
+
+#;(define-typed-syntax empty-sequence
+  [_ ≫
+   --------------------
+   [⊢ empty-sequence- (⇒ : (Sequence (U)))]])
+
+;; er, this is making everything a macro, as opposed to a procedure...
+;; think I ought to add polymorphous first :\
+#;(define-typed-syntax (sequence->list s) ≫
+  [⊢ s ≫ s- (⇒ : (~Sequence τ))]
+  #:fail-unless (pure? #'s-)
+  ------------------------------
+  [⊢ (sequence->list- s-) (⇒ : (List τ))])
+
+#;(define-typed-syntax (sequence-length s) ≫
+    [⊢ s ≫ s- (⇒ : (~Sequence τ))]
+    #:fail-unless (pure? #'s-)
+    ------------------------------
+    [⊢ (sequence-length- s-) (⇒ : Int)])
diff --git a/racket/typed/tests/sequences.rkt b/racket/typed/tests/sequences.rkt
new file mode 100644
index 0000000..3782588
--- /dev/null
+++ b/racket/typed/tests/sequences.rkt
@@ -0,0 +1,19 @@
+#lang typed/syndicate/roles
+
+(require rackunit/turnstile)
+
+(check-type empty-sequence : (Sequence (U)))
+
+(typecheck-fail (sequence-length empty-sequence))
+
+(check-type ((inst sequence-length (U)) empty-sequence)
+            : Int
+            ⇒ 0)
+
+(define sequence-length/Int (inst sequence-length Int))
+(define sequence->list/Int (inst sequence->list Int))
+(define in-list/Int (inst in-list Int))
+
+(check-type (sequence->list/Int (in-list/Int (list 3 9 20)))
+            : (List Int)
+            ⇒ (list 3 9 20))