Converting a string to int in SML -

-

in attempt create interpreter simple language in sml, struggling convert string integer. instance,

val somestring = " 1.9" int.fromstring somestring

returns:

val 1 : int option

furthermore, when try extract value option type using:

valof(int.fromstring somestring);

it returns:

val = 1 : int

i confused why still converting string integer though real number. , how can convert string int , handle errors if any.

i don't know how conversion in every implementation works, in poly/ml valid int returned if valid int has been read far - if whole string not valid int.

as molbdnilo pointed out, easier use char.isdigit function (or own allows more int cases) check if string int:

list.all char.isdigit (string.explode somestring)

concerning confusion valof, expected because saw int.fromstring returned int option. valof function defined this:

fun valof (opt: 'a option) : 'a =     case opt of         none => raise fail "option none"       | =>

so since saw int.fromstring " 1.9" returned some 1, must case valof (int.fromstring " 1.9") returns 1.


Comments

Post a Comment

Popular posts from this blog

java - Run spring boot application error: Cannot instantiate interface org.springframework.context.ApplicationListener -

-
i have spring project , try make use spring boot , run @ embadded tomcat following : https://spring.io/guides/gs/rest-service/ this application //@configuration //@enableaspectjautoproxy @springbootapplication @componentscan(basepackages = "gux.prome") public class application { public static void main(string[] args) { springapplication.run(application.class, args); } } if use maven command: mvn spring-boot:run , project starts fine, need debug , run main method @ intelij, exception occurs: exception in thread "main" java.lang.illegalargumentexception: cannot instantiate interface org.springframework.context.applicationlistener : org.springframework.boot.logging.classpathloggingapplicationlistener @ org.springframework.boot.springapplication.createspringfactoriesinstances(springapplication.java:414) @ org.springframework.boot.springapplication.getspringfactoriesinstances(springapplication.java:394) @ org.springframework.bo...
Read more

reactjs - React router and this.props.children - how to pass state to this.props.children -

-
i'm using react-router first time , don't know how think in yet. here's how i'm loading components in nested routes. entry point .js reactdom.render( <router history={hashhistory} > <route path="/" component={app}> <route path="models" component={content}> </route> </router>, document.getelementbyid('app') ); app.js render: function() { return ( <div> <header /> {this.props.children} </div> ); } so child of app content component sent in. i'm using flux , app.js has state , listens changes, don't know how pass state down this.props.children. before using react-router app.js defines children explicitly, passing state natural don't see how now. using couple of react helper methods can add state, props , whatever else this.props.children render: function() { var children = react.ch...
Read more

Excel VBA "Microsoft Windows Common Controls 6.0 (SP6)" Location Changes -

-
i have excel workbook used generate quotations customers. there main page user inputs data, , there buttons generate various pdfs , send them customer. however, 1 user consistently getting error preventing generating , sending pdfs. i beleive "microsoft windows common controls 6.0 (sp6)". it's installed on users' computers. on mine, location "c:\windows\syswow64\mscomctl.ocx" on others "c:\windows\system32\mscomctl.ocx" the user experiencing issues on 32-bit machine, "mscomctl.ocx" file should in system32. have manually put in there, , pointed common controls reference in vba it. issue seems keep reverting looking in syswow64. since folder doesn't exist, can't find it, , can't produce pdfs. i thought perhaps issue user running older version of office (2007) there users on 2013 , 2016. thought perhaps mixture of 64-bit , 32-bit users. user gets sent workbook other users (as quotation process goes further, gets passed ...
Read more