racket - how to make predicates function? in scheme -

-

I am trying to take action on future

Datatype definition 

  (define-datatype expression expression? (Num number?)) (Var-exp (var symbol?)) (Zero? -exp (exp1 expression?)) (Diff-exp (exp1 expression?) (Exp2 expression?)))   
 If the argument is # 2 (straight: const-exp 7) then print #t  
 if argument # 2 (struct: var - Exp x) Then print # f  
  (const-exp define? ...)   
 If you help me, then this is respect  
  
 
 
 So my guess is that you are reading and probably use it as your environment .  
 If this is true, you should probably use it here:  
  (define-const-exp? E) (case expression (const-exp ( num) #t) (else #f))   
 then  
  & gt; (Cost-exp? (Constant-Express 7)) # T & gt; (Consta-exp? (Vir XAP 'X)) #F

Comments

Post a Comment

Popular posts from this blog

php - PDO bindParam() fatal error -

-
I am trying to learn PDO, now I have written this small code, but it gives me a serious error: Fatal error: Call a member function at a non-object dot () ... $ con = new mysqli ("127.0.0.1", "root", "", "csvdangercheck"); $ Query = $ con- & gt; ("Id,` var1`, `var2`) values ​​(" id,: var1,: var2) ";); $ query- & gt; bypass pattern (': id', $ id); $ query- & gt; BindParam (': var1', $ VAL1); $ Query- & gt; bindParam (': var2', $ val2); $ Query-> Executed (); I Trying to use print_r ($ con-> errorInfo ()) but Fatal error: Undefined method mysqli :: errorInfo ( ) ... can someone tell me what am I missing? Flaffeh said, you have PDO Missing Mysqy, try it: $ con = new PDO ('mysql: host = 127.0.0.1; dbname = csvdangercheck', 'root', '');
Read more

php - How can I cram 6+31 numeric characters into 22 alphanumeric characters? -

-
I have a 6 digit number and a 31-digit number (such as "234536" and "201103231043330478311223582826") that I The API needs to be crawled in the same 22-character alphanumeric field that uses PHP. I tried to convert each one to 32 (using custom code could not handle the base_convert () large number) and to connect with a single-character delimiter, but It only gives me 26 characters This is a restore API, so the letters should be URI-protected. I would like to do a database table cross with two references without reference to another reference value, if possible, any suggestions? Instead use a radix of 62. This will give you 22 characters for the top, 3.35 for the pre and 17.3 for the next. & gt; & Gt; & Gt; Math.log (10 ** 6) /math.log (62) 3.3474826039165504 & gt; & Gt; & Gt; Math.log (10 ** 31) /math.log (62) 17.295326786902177
Read more

logging - How can I log both the Request.InputStream and Response.OutputStream traffic in my ASP.NET MVC3 Application for specific Actions? -

-
For a specific set of tasks, I need to log in to the incoming request inputstream as well as outgoing response. is. I am using an ActionFilterAttribute for this and overriding the OnActionExecuted and OnResultExecuted methods. So I'm starting with this idea ... Public category ActionLoggerAttribute: ActionFilterArrbit {Public Override Zero On-Offed Execution (ActionActioned Contact Filter Filter) {base.OnActionAxecuted (FilterContext); HttpRequestBase request = filterContext.HttpContext.Request; // TODO: Log the request. InputStream} Public Override Zero OnResultExecuted (ResultExecutedContext FilterContext) {base.OnResultExecuted (filterContext); HTTPRPSPointBase Response = FilterContacts Hpptex response; // TODO: Log on Response.OutputStream}} Ideally I'll hook it up with enterprise library logging because I'm already using it for error logging. Am I reaching the input and output stream at the right time? Can I easily use the Enterprise Library to log i...
Read more