Script started on 2020-03-20 10:43:23-03:00 [TERM="xterm-256color" TTY="/dev/pts/0" COLUMNS="63" LINES="16"]
]0;mfinger@animal: ~mfinger@animal:~$ sudo apt install swipl
[sudo] password for mfinger: 

Reading package lists... 0%

Reading package lists... 100%

Reading package lists... Done


Building dependency tree... 0%

Building dependency tree... 0%

Building dependency tree... 50%

Building dependency tree... 50%

Building dependency tree       


Reading state information... 0%

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Reading state information... Done

E: Unable to locate package swipl
]0;mfinger@animal: ~mfinger@animal:~$ sudo apt install swipl-plrolog
E: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 11587 (synaptic) - open (11: Resource temporarily unavailable)
N: Be aware that removing the lock file is not a solution and may break your system.
E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?
]0;mfinger@animal: ~mfinger@animal:~$ sudo apt install swi-prolog

Reading package lists... 0%

Reading package lists... 100%

Reading package lists... Done


Building dependency tree... 0%

Building dependency tree... 0%

Building dependency tree... 50%

Building dependency tree... 50%

Building dependency tree       


Reading state information... 0%

Reading state information... 0%

Reading state information... Done

swi-prolog is already the newest version (7.6.4+dfsg-2ubuntu2).
0 upgraded, 0 newly installed, 0 to remove and 15 not upgraded.
]0;mfinger@animal: ~mfinger@animal:~$ swipll
Welcome to SWI-Prolog (threaded, 64 bits, version 7.6.4)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit http://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- a = a.
true.

?- a = b.
false.

?- X = a.
X = a.

?- a = X.
X = a.

?- X = a, Y = b.
X = a,
Y = b.

?- X = a, X = b.
false.

?- a = a, a = b.
false.

?- f(X
)(X) = g(a


f(c
)(c).
X = c.

?- f(g(Y
)(Y)
) - 

= f(Z
)(Z)
)
_)
Z)

z
)(_z).
_z = g(Y).

?- 
?- f(g(Y)) = f(_z).
, Y = b.
Y = b,
_z = g(b).

?- X = f(X
)(X).
X = f(X).

?- 
?- X = f(X).
, X = a.
false.

?- 
?- X = f(X), X = a.
. =  = f(X).
X = f(X).

?- hal

?- h
?- ^D
% halt
]0;mfinger@animal: ~mfinger@animal:~$ exit
exit

Script done on 2020-03-20 10:58:18-03:00 [COMMAND_EXIT_CODE="0"]