Re: Question about in_channel???
"Douglas Lewit [email protected] [ocaml_beginners]" <[email protected]> Fri, 12 May 2017 13:28:12 -0500
| Newsgroups | gmane.comp.lang.ocaml.beginners |
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| Message-ID | <CAM0XMJQ=ASOYdnVeZzTdLkZsnBhp5GZCo-Pxr7pgHAer+0bXtQ@mail.gmail.com> |
--94eb2c0760ca3f6f6d054f57de7d Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Toby, Thanks for the reply. Regarding SML, I'm using the SML of New Jersey implementation. So far all I can gather is that the compilation command requires something like CM.make( ) but beyond that I'm really lost. I just haven't been able to find any information about this. Most of the SML examples that I have found so far are limited to using the REPL. Best, Douglas. On Fri, May 12, 2017 at 9:28 AM, Toby Kelsey [email protected] [ocaml_beginners] <[email protected]> wrote: > > > On 11/05/17 10:40, Douglas Lewit [email protected] [ocaml_beginners] > wrote: > > However, at no point in the > > program am I able to place a "close_in" command to close the in_channel > > value. Isn't that a problem? > > You need to close the file after you have the result, but before you > return from the function which opens the file. You > can use the semicolon syntax to do this: > > let myfunc filename =3D > let chan =3D open_in filename in > ... > let result =3D count_lines_helper chan ... in > (close_in chan; result) > > A good practice is to also catch any exception and close the file before > reraising the exception. This page has an > example of this: > > <https://ocaml.org/learn/tutorials/file_manipulation.html#Example> > > > Oh yes.... one last question. If someone says, "My function's type is > int" > > and someone else says, "My function's return type is int", do those two > > statements mean exactly the same thing? So if a function returns an int > > for example, then you could say the function type is int or you could s= ay > > the function's return type is int. Is that correct? > > Some programmers may conflate function type and return type when speaking > casually, but in > functional programming the type of the function 'a -> b' is distinct from > the type of the result 'b'. > > > the function's return type is int. Is that correct? I know functional > > programmers seem to avoid ( as much as possible ) using the word > "return". > > Honestly, I'm not sure why the word "return" is such a dirty word among > > functional programmers. Oh well.... I guess it's just part of the lingo > of > > the tradition, right? > > Functional pogrammers think of functions as being like mathematical > expressions. It would sound odd to say 1+2 has a > "return type" of int. > > > many ways, but.... how on earth are we supposed to compile a .sml file? > > Most (all?) implementations of SML have a compiler. Which one are you > using? > > Toby > >=20 > --94eb2c0760ca3f6f6d054f57de7d Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/htm= l4/strict.dtd"> <html> <head> </head> =20 <body style=3D"background-color: #fff;"> <span style=3D"display:none"> </span> <!--~-|**|PrettyHtmlStartT|**|-~--> <div id=3D"ygrp-mlmsg" style=3D"position:relative;"> <div id=3D"ygrp-msg" style=3D"z-index: 1;"> <!--~-|**|PrettyHtmlEndT|**|-~--> <div id=3D"ygrp-text" > =20=20=20=20=20=20 =20=20=20=20=20=20 <p><div dir=3D"ltr"><font size=3D"4">Hi Toby,</font><div><font size= =3D"4"><br></font></div><div><font size=3D"4">Thanks for the reply.=C2=A0 R= egarding SML, I'm using the SML of New Jersey implementation.=C2=A0 So = far all I can gather is that the compilation command requires something lik= e CM.make( ) but beyond that I'm really lost.=C2=A0 I just haven't = been able to find any information about this.=C2=A0 Most of the SML example= s that I have found so far are limited to using the REPL.</font></div><div>= <font size=3D"4"><br></font></div><div><font size=3D"4">Best,</font></div><= div><font size=3D"4"><br></font></div><div><font size=3D"4">Douglas.</font>= </div><div><font size=3D"4"><br></font></div></div><div class=3D"gmail_extr= a"><br><div class=3D"gmail_quote">On Fri, May 12, 2017 at 9:28 AM, Toby Kel= sey <a href=3D"mailto:[email protected]">[email protected]</a> [oca= ml_beginners] <span dir=3D"ltr"><<a href=3D"mailto:ocaml_beginners@yahoo= groups.com" target=3D"_blank">[email protected]</a>></span= > wrote:<br><blockquote class=3D"gmail_quote" style=3D"border-left:1px #ccc= solid;"> <u></u> =20 <div style=3D"background-color:#fff;"> <span>=C2=A0</span> <div id=3D"m_7679632779910439318ygrp-mlmsg"> <div id=3D"m_7679632779910439318ygrp-msg"> <div id=3D"m_7679632779910439318ygrp-text"> =20=20=20=20=20=20 =20=20=20=20=20=20 <p><span class>On 11/05/17 10:40, Douglas Lewit <a href=3D"mailto:del= [email protected]" target=3D"_blank">[email protected]</a> [ocaml_beginners] w= rote:<br> > However, at no point in the<br> > program am I able to place a "close_in" command to close th= e in_channel<br> > value. Isn't that a problem?<br> <br></span> You need to close the file after you have the result, but before you return= from the function which opens the file. You <br> can use the semicolon syntax to do this:<br> <br> let myfunc filename =3D<br> let chan =3D open_in filename in<br> ...<br> let result =3D count_lines_helper chan ... in<br> (close_in chan; result)<br> <br> A good practice is to also catch any exception and close the file before re= raising the exception. This page has an <br> example of this:<br> <br> <<a href=3D"https://ocaml.org/learn/tutorials/file_manipulation.html#Exa= mple" target=3D"_blank">https://ocaml.org/learn/<wbr>tutorials/file_manipul= ation.<wbr>html#Example</a>><span class><br> <br> > Oh yes.... one last question. If someone says, "My function'= s type is int"<br> > and someone else says, "My function's return type is int"= ;, do those two<br> > statements mean exactly the same thing? So if a function returns an i= nt<br> > for example, then you could say the function type is int or you could = say<br> > the function's return type is int. Is that correct?<br> <br></span> Some programmers may conflate function type and return type when speaking c= asually, but in<br> functional programming the type of the function 'a -> b' is dist= inct from the type of the result 'b'.<span class><br> <br> > the function's return type is int. Is that correct? I know funct= ional<br> > programmers seem to avoid ( as much as possible ) using the word "= ;return".<br> > Honestly, I'm not sure why the word "return" is such a d= irty word among<br> > functional programmers. Oh well.... I guess it's just part of the= lingo of<br> > the tradition, right?<br> <br></span> Functional pogrammers think of functions as being like mathematical express= ions. It would sound odd to say 1+2 has a <br> "return type" of int.<span class><br> <br> > many ways, but.... how on earth are we supposed to compile a .sml file= ?<br> <br></span> Most (all?) implementations of SML have a compiler. Which one are you using= ?<br> <br> Toby<br> <br> </p> </div> =20=20=20=20=20 =20=20=20=20 <div style=3D"color:#fff;height:0;"></div> </div> =20=20 </div></div></blockquote></div><br></div> </p> </div> =20=20=20=20=20 <!--~-|**|PrettyHtmlStart|**|-~--> <div style=3D"color: #fff; height: 0;">__._,_.___</div> =20=20=20=20=20=20=20=20=20=20 =20=20 =20 =20=20=20=20 <div style=3D"clear:both"> </div> <div id=3D"fromDMARC" style=3D"margin-top: 10px;"> <hr style=3D"height:2px ; border-width:0; color:#E3E3E3; background= -color:#E3E3E3;"> Posted by: Douglas Lewit <[email protected]> <hr style= =3D"height:2px ; border-width:0; color:#E3E3E3; background-color:#E3E3E3;"> </div> <div style=3D"clear:both"> </div> <table cellspacing=3D4px style=3D"margin-top: 10px; margin-bottom: 10px= ; color: #2D50FD;"> <tbody> <tr> <td style=3D"font-size: 12px; font-family: arial; font-weight: bo= ld; padding: 7px 5px 5px;" > <a style=3D"text-decoration: none; color: #2D50FD= " href=3D"https://groups.yahoo.com/neo/groups/ocaml_beginners/conversations= /messages/14809;_ylc=3DX3oDMTJxdWtndGJzBF9TAzk3MzU5NzE0BGdycElkAzQ5OTkxOTQE= Z3Jwc3BJZAMxNzA1MDA2NzY0BG1zZ0lkAzE0ODA5BHNlYwNmdHIEc2xrA3JwbHkEc3RpbWUDMTQ= 5NDYxMzY5NA--?act=3Dreply&messageNum=3D14809">Reply via web post</a> </td> <td>•</td> <td style=3D"font-size: 12px; font-family: arial; padding: 7px 5p= x 5px;" > <a href=3D"mailto:[email protected]?subject=3DRe%3A%20%22ocaml_= beginners%22%3A%3A%5B%5D%20Question%20about%20in_channel%3F%3F%3F" style=3D= "text-decoration: none; color: #2D50FD;"> Reply to sender </a> </td> <td>•</td> <td style=3D"font-size: 12px; font-family: arial; padding: 7px 5p= x 5px;"> <a href=3D"mailto:[email protected]?subject=3DRe%= 3A%20%22ocaml_beginners%22%3A%3A%5B%5D%20Question%20about%20in_channel%3F%3= F%3F" style=3D"text-decoration: none; color: #2D50FD"> Reply to group </a> </td> <td>•</td> <td style=3D"font-size: 12px; font-family: arial; padding: 7px 5p= x 5px;" > <a href=3D"https://groups.yahoo.com/neo/groups/ocaml_beginners/= conversations/newtopic;_ylc=3DX3oDMTJlOWZ1aXZhBF9TAzk3MzU5NzE0BGdycElkAzQ5O= TkxOTQEZ3Jwc3BJZAMxNzA1MDA2NzY0BHNlYwNmdHIEc2xrA250cGMEc3RpbWUDMTQ5NDYxMzY5= NA--" style=3D"text-decoration: none; color: #2D50FD">Start a New Topic</a> </td> <td>•</td> <td style=3D"font-size: 12px; font-family: arial; padding: 7px 5p= x 5px;color: #2D50FD;" > <a href=3D"https://groups.yahoo.com/neo/groups/= ocaml_beginners/conversations/topics/14806;_ylc=3DX3oDMTM2dTVnc3AyBF9TAzk3M= zU5NzE0BGdycElkAzQ5OTkxOTQEZ3Jwc3BJZAMxNzA1MDA2NzY0BG1zZ0lkAzE0ODA5BHNlYwNm= dHIEc2xrA3Z0cGMEc3RpbWUDMTQ5NDYxMzY5NAR0cGNJZAMxNDgwNg--" style=3D"text-dec= oration: none; color: #2D50FD;">Messages in this topic</a> (3) </td> </tr> </tbody> </table> =20=20=20=20=20=20=20=20 <div id=3D"megaphoneModule"> <hr style=3D"height:2px ; border-width:0; color:#E3E3E3; backgr= ound-color:#E3E3E3;"> <div> <div class=3D"stream" style=3D"margin-bottom:10px;"> <div style=3D"background-color:white;"> <div class=3D"sn-img" style=3D"display:inline;"><img name=3D"tn= _file" style=3D"padding:0px 10px;vertical-align:top;margin-top:5px;" src=3D= "https://s.yimg.com/ru/static/images/yg/img/megaphone/1464031581_phpFA8bON"= height=3D"82" width=3D"82"></div> <div class=3D"mod-txt" style=3D"display:inline-block;"> <a rel=3D"nofollow" name=3D"sub_url" target=3D"_blank" href= =3D"https://yho.com/1wwmgg" style=3D"color:#0000FF;display:block;margin-lef= t:5px;text-decoration:none;"><span style=3D"font-size:15px;">Have you tried= the highest rated email app?</span></a> <div style=3D"max-width:530px;padding:2px 5px;">With 4.5 st= ars in iTunes, the Yahoo Mail app is the highest rated email app on the mar= ket. 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