提交: 9874abe37efb128d50beb15094374b5e144a39bb - cammy (git)

A categorical programming language

Commit MetaInfo

• 修订版: 9874abe37efb128d50beb15094374b5e144a39bb (tree)
• 时间: 2021-08-09 05:51:52
• 作者: Corbin <cds@corb...>
• Commiter: Corbin

Log Message

Require nats to be positive.

更改概述

• modified: finish.py
• modified: stub.scm

差异

--- a/finish.py
+++ b/finish.py
@@ -5,7 +5,7 @@ import sys
 parsers = {
     "unit": "string->unit",
     "bool": "string->boolean",
-    "nat": "string->number",
+    "nat": "string->nat",
     "nat * nat": "string->int",
 }
 

--- a/stub.scm
+++ b/stub.scm
@@ -1,3 +1,5 @@
+(import (chicken condition))
+
 (define id (lambda (x) x))
 (define (comp f g) (lambda (x) (g (f x))))
 
@@ -30,6 +32,10 @@
 
 (define (string->unit s) '())
 (define (string->boolean s) (equal? s "true"))
+(define (string->nat s)
+  (let ((i (string->number s)))
+    (if (< i 0) (signal (condition '(exn message "nats must be positive")))
+      i)))
 (define (string->int s)
   (let ((i (string->number s))) (if (< i 0) (cons 0 (abs i)) (cons i 0))))
 (define (fold-left kn kc l) (if (null? l) kn (kc (car l) (fold-left kn kc (cdr l)))))