Re: [Bug-apl] [PATCH]: allow using lambdas in ]USERCMD

[Alexey Veretennikov]

Hi,

I'm updating the ]USERCMD functionality which is already non-standard extension 
in GNU
APL. Similar extension exists in Dyalog APL for quite many years as
well. These commands targeted use in the interpreter and have nothing to do
with a new syntax. 
What I did is just fixed its limitation where I always had to
create a named function to add a user command.

P.S. Example with ]pwd was bogus, the proper one is

      ]usercmd ]pwd {⎕FIO 30 ⍵}
    User-defined command ]pwd installed.
      ]pwd
/Users/alexeyv


Blake McBride <address@hidden> writes:

> Not sure I like this. Doesn't seem like APL. You are mangling program-ability 
> with system commands. APL
> has no history of that. It may be an okay idea, but it's not APL.
>
> Adding program-ability to system commands is essentially adding a whole new 
> syntax to APL.
>
> Just one opinion.
>
> Blake
>
> On Wed, Feb 22, 2017 at 4:18 PM, Alexey Veretennikov <address@hidden> wrote:
>
>  Hi,
>
>  The proposed patch allows usage of dfns as a ]USERCMD.
>  The mode (monadic or dyadic) is not needed since it is derived from the
>  lambda function itself.
>
>  Possibility to use lambdas as a user commands allows to have commands
>  without polluting the global namespace with the function names.
>
>  Usage example:
>
>  ]usercmd ]pwd {⎕FIO 30 ⍵ ← ⍺}
>  User-defined command ]pwd installed.
>
>  ]pwd
>  /Users/alexeyv/Sources/apl-svn/src
>
>  ]usercmd ]cd {⎕FIO[54] (⎕IO+1) ⊃ ⍵ ← ⍺}
>  User-defined command ]cd installed.
>
>  ]cd /Users/alexeyv
>  0
>
>  ]pwd
>  /Users/alexeyv
>
>  --
>  Br,
>  /Alexey
>
>  Index: src/Command.cc
>  ===================================================================
>  --- src/Command.cc (revision 891)
>  +++ src/Command.cc (working copy)
>  @@ -1277,6 +1277,7 @@
>  // ]USERCMD REMOVE ]existing-command
>  // ]USERCMD ]new-command APL-fun
>  // ]USERCMD ]new-command APL-fun mode
>  + // ]USERCMD ]new-command LAMBDA-fun
>  //
>  if (args.size() == 0)
>  {
>  @@ -1321,14 +1322,54 @@
>  return;
>  }
>
>  - if (args.size() > 3)
>  + // check if the user command is not followed by the string
>  + if (args.size() == 1)
>  + {
>  + out << "BAD COMMAND+" << endl;
>  + MORE_ERROR() << "user command syntax in ]USERCMD: ]new-command APL-fun 
> [mode]";
>  + return;
>  + }
>  + UCS_string command_name = args[0];
>  + UCS_string apl_fun = args[1];
>  + int mode = 0;
>  +
>  + // check if lambda
>  + bool is_lambda = false;
>  + if (apl_fun[0] == '{')
>  {
>  + // looks like the user command is a lambda function.
>  + UCS_string result;
>  + // lambdas could contain spaces, collect all arguments in one string
>  + for (int i = 1; i < args.size(); ++ i)
>  + {
>  + result << args[i];
>  + }
>  + // check if lamda-function closed properly
>  + if (result.last() == '}')
>  + {
>  + is_lambda = true;
>  + apl_fun = result;
>  + // determine the mode: if both alpha and omega present, assume dyadic,
>  + // otherwise - monadic usage
>  + mode = (apl_fun.contains(UNI_OMEGA) && apl_fun.contains(UNI_ALPHA)) ? 1 : 
> 0;
>  + }
>  + else
>  + {
>  + out << "BAD COMMAND+" << endl;
>  + MORE_ERROR() << "not found closing } in lambda function";
>  + return;
>  + }
>  + }
>  +
>  + if (args.size() > 3 && !is_lambda)
>  + {
>  out << "BAD COMMAND+" << endl;
>  MORE_ERROR() << "too many parameters in command ]USERCMD";
>  return;
>  }
>
>  -const int mode = (args.size() == 3) ? args[2].atoi() : 0;
>  + // check mode
>  + if (!is_lambda && args.size() == 3) mode = args[2].atoi();
>  if (mode < 0 || mode > 1)
>  {
>  out << "BAD COMMAND+" << endl;
>  @@ -1339,11 +1380,11 @@
>
>  // check command name
>  //
>  - loop(c, args[0].size())
>  + loop(c, command_name.size())
>  {
>  bool error = false;
>  - if (c == 0) error = error || args[0][c] != ']';
>  - else error = error || !Avec::is_symbol_char(args[0][c]);
>  + if (c == 0) error = error || command_name[c] != ']';
>  + else error = error || !Avec::is_symbol_char(command_name[c]);
>  if (error)
>  {
>  out << "BAD COMMAND+" << endl;
>  @@ -1355,28 +1396,31 @@
>  // check conflicts with existing commands
>  //
>  #define cmd_def(cmd_str, _cod, _arg, _hint) \
>  - if (check_name_conflict(out, cmd_str, args[0])) return;
>  + if (check_name_conflict(out, cmd_str, command_name)) return;
>  #include "Command.def"
>  - if (check_redefinition(out, args[0], args[1], mode))
>  + if (check_redefinition(out, command_name, apl_fun, mode))
>  {
>  out << " User-defined command "
>  - << args[0] << " installed." << endl;
>  + << command_name << " installed." << endl;
>  return;
>  }
>
>  // check APL function name
>  - //
>  - loop(c, args[1].size())
>  + // Only needed when not a lambda function
>  + if (!is_lambda)
>  {
>  - if (!Avec::is_symbol_char(args[1][c]))
>  - {
>  - out << "BAD COMMAND+" << endl;
>  - MORE_ERROR() << "bad APL function name in command ]USERCMD";
>  - return;
>  - }
>  + loop(c, apl_fun.size())
>  + {
>  + if (!Avec::is_symbol_char(apl_fun[c]))
>  + {
>  + out << "BAD COMMAND+" << endl;
>  + MORE_ERROR() << "bad APL function name in command ]USERCMD";
>  + return;
>  + }
>  + }
>  }
>
>  -user_command new_user_command = { args[0], args[1], mode };
>  +user_command new_user_command = { command_name, apl_fun, mode };
>  user_commands.append(new_user_command);
>
>  out << " User-defined command "
>
>

-- 
Br,
/Alexey