提交: 8f46d9690f137bd171003b4d4754d017a75b9b81 - cammy (git)

A categorical programming language

Commit MetaInfo

• 修订版: 8f46d9690f137bd171003b4d4754d017a75b9b81 (tree)
• 时间: 2021-08-14 09:19:57
• 作者: Corbin <cds@corb...>
• Commiter: Corbin

Log Message

Add map() functor on lists.

A little bit of abstract thought suggests that fold() isn't enough to do
this, but I'm very open to constructive proofs otherwise.

更改概述

• modified: cammy.txt
• modified: finish.py
• modified: frame/frame.ml
• add: hive/bool/is_left.cammy
• modified: stub.ml
• modified: stub.scm
• modified: todo.txt

差异

--- a/cammy.txt
+++ b/cammy.txt
@@ -50,6 +50,7 @@ Given x : 1 → X and f : X → X, pr(x, f) : N → X
 
 nil : 1 → [X]
 cons : X × [X] → X
+Given f : X → Y, map(f) : [X] → [Y]
 Given x : 1 → Y and f : X × Y → Y, fold(x, f) : [X] → Y
 
 Combinators with (*) are provided by OCaml by default; the others are in a

--- a/finish.py
+++ b/finish.py
@@ -26,6 +26,7 @@ with open("stub.scm", "r", encoding="utf-8") as handle:
 with open(sys.argv[-2], "r", encoding="utf-8") as handle:
     program = handle.read().strip()
     program = program.replace("cons", "cammy-cons")
+    program = program.replace("map", "cammy-map")
     print("(define program {})".format(program))
 
 print("""

--- a/frame/frame.ml
+++ b/frame/frame.ml
@@ -4,7 +4,7 @@ module CodeCache = Map.Make (String)
 
 let primitives =
   "id comp ignore fst snd pair left right case assl assr swap dup curry \
-   uncurry app name zero succ for nil cons fold t f not conj disj"
+   uncurry app name zero succ for nil cons map fold t f not conj disj"
 
 let filter =
   List.fold_left

--- /dev/null
+++ b/hive/bool/is_left.cammy
@@ -0,0 +1 @@
+(case (comp ignore t) (comp ignore f))

--- a/stub.ml
+++ b/stub.ml
@@ -25,4 +25,5 @@ let succ n = S n
 let rec pr x f n = match n with O -> x () | S p -> f (pr x f p)
 let nil () = []
 let cons (x, xs) = x :: xs
+let map f = List.map f
 let fold x f = List.fold_left (fun y z -> f (z, y)) (x ())

--- a/stub.scm
+++ b/stub.scm
@@ -30,6 +30,7 @@
 
 (define nil (lambda (x) '()))
 (define cammy-cons (lambda (xy) (cons (car xy) (cdr xy))))
+(define (cammy-map f) (lambda (l) (map f l)))
 (define (fold x f)
   (lambda (l) (if (null? l) (x '()) (f (cons (car l) ((fold x f) (cdr l)))))))
 

--- a/todo.txt
+++ b/todo.txt
@@ -1,5 +1,4 @@
 * list/eq : [X × X, 2] → [[X] × [X], 2]
 * list/zip : [X] × [Y] → [X × Y]
-* list/map : [X, Y] → [[X], [Y]]
 * list/tail : [X] → [X]
 * rat