J in Raku (and Perl)

j.raku

#!/usr/bin/env raku

use NativeCall;

class J is repr('CPointer') {

    my constant $BIN = "/opt/j903/bin";
    my constant $LIB = "$BIN/libj.so";
    my constant $PRO = "$BIN/profile.ijs";
    
    sub JInit ()       returns J      is native($LIB) { * }
    sub JDo   (J, Str) returns uint32 is native($LIB) { * }
    sub JGetR (J)      returns Str    is native($LIB) { * }

    method new() {
        my $j = JInit();
        $j.do("0!:0<'$PRO'[BINPATH_z_=:'$BIN'[ARGV_z_=:''");
        return $j;
    }
    method do(Str \c) {
        JDo(self, c)
    }
    method getr() {
        JGetR(self)
    }
}

my $j = J.new;

loop {
    my $expr = prompt('   ');
    $j.do($expr);  # returns 0 on success
    print $j.getr();
}

For Windows users, you just need to modify the $BIN and $LIB, eg.

my constant $BIN = "C:/Program Files/J902/bin";
my constant $LIB = "$BIN/j.dll";

Including Perl because why not

use v5.36;
use warnings qw< FATAL all >;
use FFI::Platypus 2.00;

my $BIN = "/opt/j903/bin";
my $LIB = "$BIN/libj.so";
my $PRO = "$BIN/profile.ijs";

my $ffi = FFI::Platypus->new(api => 2);

$ffi->lib($LIB);
$ffi->attach(JInit => []                   => 'opaque');
$ffi->attach(JDo   => ['opaque', 'string'] => 'uint32');
$ffi->attach(JGetR => ['opaque']           => 'string');

my $j = JInit();
JDo($j, "0!:0<'$PRO'[BINPATH_z_=:'$BIN'[ARGV_z_=:''");

while (1) {
    print '   ';
    chomp(my $expr = readline());
    JDo($j, $expr);
    print JGetR($j);
}   

Now a Raku module: Inline::J