digitalmars.D - [your code here] Pure RPN calculator

Max Haughton (6/6) Jul 25 2017 Semi-Functional/pure RPN calculator:

GrrrrrAngryMan (4/10) Jul 25 2017 Answer to this
Seb (15/21) Jul 25 2017 Max, this is a great example!

Timon Gehr (11/25) Jul 26 2017 import std.stdio,std.string,std.algorithm,std.conv;

Vladimir Panteleev (4/15) Jul 28 2017 That's pretty great!

Timon Gehr (11/25) Jul 26 2017 import std.stdio, std.string, std.algorithm, std.conv;

Timon Gehr (2/29) Jul 26 2017 (Sorry for the double post. Internet connection problem.)

Iakh (2/10) Jul 26 2017 What does "case [c]:" mean?

Mike Wey (5/17) Jul 26 2017 In the static foreach c is a `immutable char` by putting it between [

Patrick Schluter (3/19) Jul 26 2017 That's why some comments in the code would go a long way in

Max Haughton <maxhaton gmail.com> writes:

Semi-Functional/pure RPN calculator: 
https://run.dlang.io/is/JGkBZx

This is probably too long, but it demonstrates the compiler 
enforced safety and purity (State is passed through the fold), 
while also showing off the higher level parts of Phobos (Use of 
fold).

Jul 25 2017

GrrrrrAngryMan <gam gam.gam> writes:

On Tuesday, 25 July 2017 at 21:13:54 UTC, Max Haughton wrote:
 Semi-Functional/pure RPN calculator: 
 https://run.dlang.io/is/JGkBZx

 This is probably too long, but it demonstrates the compiler 
 enforced safety and purity (State is passed through the fold), 
 while also showing off the higher level parts of Phobos (Use of 
 fold).

Answer to this 
https://forum.dlang.org/post/dhuvztizmqysqsepmpgh forum.dlang.org.
This is exactly what the author looked for.

Jul 25 2017

Seb <seb wilzba.ch> writes:

On Tuesday, 25 July 2017 at 21:13:54 UTC, Max Haughton wrote:
 Semi-Functional/pure RPN calculator: 
 https://run.dlang.io/is/JGkBZx

 This is probably too long, but it demonstrates the compiler 
 enforced safety and purity (State is passed through the fold), 
 while also showing off the higher level parts of Phobos (Use of 
 fold).

Max, this is a great example!
However, as you noticed it's a bit long and in fact in its 
current state it wouldn't look good:

http://imgur.com/a/KwczM

If there's no chance to make it shorter, my suggestion 
considering that there are two other ideas in the queue with a 
similar length problem:

https://github.com/dlang/dlang.org/pull/1759
https://github.com/dlang/dlang.org/pull/1762

would be to find a new home for such "one-page" D example. We 
plan to restructure the DTour (tour.dlang.org) anyways, so how 
about adding a new section like "D in action" to it?

-> I have opened a discussion: 
https://github.com/dlang-tour/english/issues/194

Jul 25 2017

Timon Gehr <timon.gehr gmx.ch> writes:

On 26.07.2017 04:37, Seb wrote:
 On Tuesday, 25 July 2017 at 21:13:54 UTC, Max Haughton wrote:
 Semi-Functional/pure RPN calculator: https://run.dlang.io/is/JGkBZx

 This is probably too long, but it demonstrates the compiler enforced 
 safety and purity (State is passed through the fold), while also 
 showing off the higher level parts of Phobos (Use of fold).

 
 Max, this is a great example!
 However, as you noticed it's a bit long and in fact in its current state 
 it wouldn't look good:
 
 http://imgur.com/a/KwczM
 
 If there's no chance to make it shorter,

import std.stdio,std.string,std.algorithm,std.conv;
void main(){
     readln.split.fold!((stack,op){
         switch(op){
             static foreach(c;"+-*/") case [c]:
                 return stack[0..$-2]~mixin("stack[$-2] "~c~" stack[$-1]");
             default: return stack~op.to!real;
         }
     })((real[]).init).writeln;
}

Jul 26 2017

Vladimir Panteleev <thecybershadow.lists gmail.com> writes:

On Wednesday, 26 July 2017 at 09:45:07 UTC, Timon Gehr wrote:
 import std.stdio,std.string,std.algorithm,std.conv;
 void main(){
     readln.split.fold!((stack,op){
         switch(op){
             static foreach(c;"+-*/") case [c]:
                 return stack[0..$-2]~mixin("stack[$-2] "~c~" 
 stack[$-1]");
             default: return stack~op.to!real;
         }
     })((real[]).init).writeln;
 }

That's pretty great!

Submitted:
https://github.com/dlang/dlang.org/pull/1848

Jul 28 2017

Timon Gehr <timon.gehr gmx.ch> writes:

On 26.07.2017 04:37, Seb wrote:
 On Tuesday, 25 July 2017 at 21:13:54 UTC, Max Haughton wrote:
 Semi-Functional/pure RPN calculator: https://run.dlang.io/is/JGkBZx

 This is probably too long, but it demonstrates the compiler enforced 
 safety and purity (State is passed through the fold), while also 
 showing off the higher level parts of Phobos (Use of fold).

 
 Max, this is a great example!
 However, as you noticed it's a bit long and in fact in its current state 
 it wouldn't look good:
 
 http://imgur.com/a/KwczM
 
 If there's no chance to make it shorter,

import std.stdio, std.string, std.algorithm, std.conv;
void main(){
     readln.split.fold!((stack,op){
         switch(op){
             static foreach(c;"+-*/") case [c]:
                 return stack[0..$-2]~mixin("stack[$-2] "~c~" stack[$-1]");
             default: return stack~op.to!real;
         }
     })((real[]).init).writeln;
}

Jul 26 2017

Timon Gehr <timon.gehr gmx.ch> writes:

On 26.07.2017 11:45, Timon Gehr wrote:
 On 26.07.2017 04:37, Seb wrote:
 On Tuesday, 25 July 2017 at 21:13:54 UTC, Max Haughton wrote:
 Semi-Functional/pure RPN calculator: https://run.dlang.io/is/JGkBZx

 This is probably too long, but it demonstrates the compiler enforced 
 safety and purity (State is passed through the fold), while also 
 showing off the higher level parts of Phobos (Use of fold).

 Max, this is a great example!
 However, as you noticed it's a bit long and in fact in its current 
 state it wouldn't look good:

 http://imgur.com/a/KwczM

 If there's no chance to make it shorter,

 
 import std.stdio, std.string, std.algorithm, std.conv;
 void main(){
      readln.split.fold!((stack,op){
          switch(op){
              static foreach(c;"+-*/") case [c]:
                  return stack[0..$-2]~mixin("stack[$-2] "~c~" stack[$-1]");
              default: return stack~op.to!real;
          }
      })((real[]).init).writeln;
 }
 

(Sorry for the double post. Internet connection problem.)

Jul 26 2017

Iakh <iaktakh gmail.com> writes:

On Wednesday, 26 July 2017 at 09:46:45 UTC, Timon Gehr wrote:
      readln.split.fold!((stack,op){
          switch(op){
              static foreach(c;"+-*/") case [c]:
                  return stack[0..$-2]~mixin("stack[$-2] "~c~" 
 stack[$-1]");
              default: return stack~op.to!real;
          }
      })((real[]).init).writeln;


What does "case [c]:" mean?

Jul 26 2017

Mike Wey <mike-wey example.com> writes:

On 26-07-17 16:40, Iakh wrote:
 On Wednesday, 26 July 2017 at 09:46:45 UTC, Timon Gehr wrote:
      readln.split.fold!((stack,op){
          switch(op){
              static foreach(c;"+-*/") case [c]:
                  return stack[0..$-2]~mixin("stack[$-2] "~c~" 
 stack[$-1]");
              default: return stack~op.to!real;
          }
      })((real[]).init).writeln;


 
 What does "case [c]:" mean?
 

In the static foreach c is a `immutable char` by putting it between [ 
and ] you create an array of immutable characters (string).

-- 
Mike Wey

Jul 26 2017

Patrick Schluter <Patrick.Schluter bbox.fr> writes:

On Wednesday, 26 July 2017 at 17:12:00 UTC, Mike Wey wrote:
 On 26-07-17 16:40, Iakh wrote:
 On Wednesday, 26 July 2017 at 09:46:45 UTC, Timon Gehr wrote:
      readln.split.fold!((stack,op){
          switch(op){
              static foreach(c;"+-*/") case [c]:
                  return stack[0..$-2]~mixin("stack[$-2] 
 "~c~" stack[$-1]");
              default: return stack~op.to!real;
          }
      })((real[]).init).writeln;


 
 What does "case [c]:" mean?
 

 In the static foreach c is a `immutable char` by putting it 
 between [ and ] you create an array of immutable characters 
 (string).

That's why some comments in the code would go a long way in 
lifting such issues.

Jul 26 2017

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