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

reply 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
next sibling parent 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
prev sibling parent reply 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
next sibling parent reply 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[$-1]"); default: return stack~op.to!real; } })((real[]).init).writeln; }
Jul 26
parent Vladimir Panteleev <thecybershadow.lists gmail.com> writes:
On Wednesday, 26 July 2017 at 09:45:07 UTC, Timon Gehr wrote:
 import std.stdio,std.string,std.algorithm,std.conv;
 void main(){
     readln.split.fold!((stack,op){
         switch(op){
             static foreach(c;"+-*/") case [c]:
                 return stack[0..$-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
prev sibling parent reply 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
parent reply 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[$-1]"); default: return stack~op.to!real; } })((real[]).init).writeln; }
(Sorry for the double post. Internet connection problem.)
Jul 26
parent reply Iakh <iaktakh gmail.com> writes:
On Wednesday, 26 July 2017 at 09:46:45 UTC, Timon Gehr wrote:
      readln.split.fold!((stack,op){
          switch(op){
              static foreach(c;"+-*/") case [c]:
                  return stack[0..$-2]~mixin("stack[$-2] "~c~" 
 stack[$-1]");
              default: return stack~op.to!real;
          }
      })((real[]).init).writeln;
What does "case [c]:" mean?
Jul 26
parent reply 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[$-1]");
              default: return stack~op.to!real;
          }
      })((real[]).init).writeln;
What does "case [c]:" mean?
In the static foreach c is a `immutable char` by putting it between [ and ] you create an array of immutable characters (string). -- Mike Wey
Jul 26
parent Patrick Schluter <Patrick.Schluter bbox.fr> writes:
On Wednesday, 26 July 2017 at 17:12:00 UTC, Mike Wey wrote:
 On 26-07-17 16:40, Iakh wrote:
 On Wednesday, 26 July 2017 at 09:46:45 UTC, Timon Gehr wrote:
      readln.split.fold!((stack,op){
          switch(op){
              static foreach(c;"+-*/") case [c]:
                  return stack[0..$-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