Q: the Shen type system, and (put ...) and (get ...)

[Antti Ylikoski]

There is one feature about Shen which is not clear to me.

After one switches the type checker (tc +) on, the property setting

and getting functions (put ...) and (get ...) generate a type error.

Below is a sample run.

------------------------------------------------------------

antti@antti-HP-Compaq-dc7100-SFF-PE271ET ~/ShenANN $ ./Shen

Shen, copyright (C) 2010-2015 Mark Tarver

www.shenlanguage.org, Shen 19.2

running under Common Lisp, implementation: CLisp

port 1.9 ported by Mark Tarver

(0-) (put andy surname "Ylikoski")

"Ylikoski"

(1-) (put andy education dr)

dr

(2-) (put andy age 56)

56

(3-) (get andy age)

56

(4-) (tc +)

true

(5+) (put antti surname "Ylikoski")

type error

(6+) (put antti education dr)

type error

(7+) (put antti age 56)

type error

(8+) (tc -)

false : boolean

(9-) (QUIT)

antti@antti-HP-Compaq-dc7100-SFF-PE271ET ~/ShenANN $

------------------------------------------------------------

What might be happening?

yours, A. J. Y.

Helsinki, Finland, the E.U.

[Mark Thom]

It's because there are no default rules for property lists.

You can add your own easily enough, as I do in this blog entry:

http://mthom.github.io/blog/2016/10/10/poor-man-s-dynamic-dispatch-with-types-in-shen/

[Antti Ylikoski]

Thank you very much, but I'm not expert enough to make this one

actually work.

Could someone more knowledgeable help?

I tried the below mentioned one:

------------------------------------------------------------

\\ AJY 2016-12-21

(datatype property-types

______________________________

put: (unit --> unit --> unit --> unit);

______________________________

get: (unit --> unit --> unit);

)

------------------------------------------------------------

It will load, but it does not work:

------------------------------------------------------------

antti@antti-HP-Compaq-dc7100-SFF-PE271ET ~/types $ ./Shen

Shen, copyright (C) 2010-2015 Mark Tarver

www.shenlanguage.org, Shen 19.2

running under Common Lisp, implementation: CLisp

port 1.9 ported by Mark Tarver

(0-) (tc +)

true

(1+) (load "prop.shen")

type#property-types : symbol

run time: 0.06799999997019768 secs

typechecked in 30 inferences

loaded : symbol

(2+) (put antti education dr)

type error

(3+) (get antti education)

type error

(4+) (tc -)

false : boolean

(5-) (QUIT)

antti@antti-HP-Compaq-dc7100-SFF-PE271ET ~/types $ 

------------------------------------------------------------

Some wise help would be very much appreciated.

yours, A. J. Y.

E.U.

[Mark Tarver]

Your axioms require antti, education etc. to be of type unit.

Mark

[Antti Ylikoski]

Yes; But I understood that the type "unit" indicates that there is

there no type information attached to the objects.

IOW, I attempted to make a LISP-style typeless put/get arrangement.

I also tried the below:

------------------------------------------------------------

\\ AJY 2016-12-21

(datatype property-types

______________________________

put: (symbol --> symbol --> symbol --> symbol);

______________________________

get: (symbol --> symbol --> symbol);

)

------------------------------------------------------------

but I still will get the type error:

------------------------------------------------------------

antti@antti-HP-Compaq-dc7100-SFF-PE271ET ~/types $ ./Shen

Shen, copyright (C) 2010-2015 Mark Tarver

www.shenlanguage.org, Shen 19.2

running under Common Lisp, implementation: CLisp

port 1.9 ported by Mark Tarver

(0-) (tc +)

true

(1+) (load "prop2.shen")

type#property-types : symbol

run time: 0.06799999997019768 secs

typechecked in 30 inferences

loaded : symbol

(2+) (put antti age middle)

type error

(3+) (get antti age)

type error

(4+) (tc -)

false : boolean

(5-) (QUIT)

antti@antti-HP-Compaq-dc7100-SFF-PE271ET ~/types $

------------------------------------------------------------

yours, AJY

[Mark Tarver]

Afraid not!

Mark

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[Antti Ylikoski]

Mark:

Could you be more specific about that statement?

I mean that if I repeatedly will get errors, which you cannot reproduce, then it is fairly certain that my hardware/software platform is flawed.

I feel that we can be certain that Shen is OK.  But I have previously been suspecting the GNU/Linux/CLisp platform.

yours, AJY

The E.U.

Afraid not!

Mark

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[Bruno Deferrari]

On Fri, Dec 23, 2016 at 2:08 AM, Antti Ylikoski
<antti.y...@gmail.com> wrote:
> Mark:
>
> Could you be more specific about that statement?
>
> I mean that if I repeatedly will get errors, which you cannot reproduce,
> then it is fairly certain that my hardware/software platform is flawed.
>
> I feel that we can be certain that Shen is OK. But I have previously been
> suspecting the GNU/Linux/CLisp platform.
>
> yours, AJY
> The E.U.
>

Your Shen install is fine, it is just that the way you are trying to
type put/get (which only take the number of arguments you are using
because of macros) will not work. Try this:

(datatype property-type-symbols
Value : symbol;
__________________
(put Var Prop Value) : symbol;

__________________
(get Var Prop) : symbol;)

You can enable 'spy' mode to see what the type checking is doing with
(spy +) before executing the type expression to be typechecked, try
before executing a get or put expression after having used your type
definition and hit enter until it fails and you will see why your
version doesn't work (see what "put : (symbol --> symbol --> symbol
--> symbol)" is trying to be unified with).

--
BD

[Antti Ylikoski]

I solved the problem, with some meditations.

The below mentioned works:

------------------------------------------------------------

\\

\\ AJY and Bruno Deferrari 2016-12-23

\\

\\ After Dr Tarver's solution to an earlier problem

(datatype unit

 _________

A : (mode unit -);)

(datatype properties

  Var: unit;

  Prop: unit;

  Value: unit;

__________________

  (put Var Prop Value) : unit;

  __________________

  (get Var Prop) : unit;

)

------------------------------------------------------------

Below is a sample run:

------------------------------------------------------------

antti@antti-HP-Compaq-dc7100-SFF-PE271ET ~/types $ srrepl

Loading.... Completed in 7.65 seconds.

Shen, copyright (C) 2010-2015 Mark Tarver

www.shenlanguage.org, Shen 18.1

running under Ruby, implementation: ruby 2.3.1

port 0.15.1 ported by Greg Spurrier

(0-) (tc +)

true

(1+) (load "props.shen")

type#unit : symbol

type#properties : symbol

run time: 0.423755407333374 secs

typechecked in 42 inferences

loaded : symbol

(2+) (put antti surname "Ylikoski")

"Ylikoski" : unit

(3+) (put antti country finland)

finland : unit

(4+) (put antti age 56)

56 : unit

(5+) (get antti age)

56 : unit

(6+) (get antti surname)

"Ylikoski" : unit

(7+) (get antti country)

finland : unit

(8+) (quit)

antti@antti-HP-Compaq-dc7100-SFF-PE271ET ~/types $

------------------------------------------------------------

I recall one British individual over the Internet IRC who said to me,

"Bad workman, blames his tools".

Once again we can see that Shen is reliable, and it is OK.

yours, AJY

E.U.

PS.  This only is a temporary solution; Mark once said something to

the effect that disabling the type checking like this is like an atom

bomb.  I shall devise something more clever for this problem.

[Mark Tarver]

You can actually reduce this to

(datatype properties

  ____________________________

  (put Var Prop Value) : unit;

  ______________________

  (get Var Prop) : unit;)

which is shorter and equivalent since you say that everything is a unit.  However this allows you to write

(put a b (+ 3 c)) 

This might be better.

(datatype properties

  ____________________________

  put : (A --> B --> C --> C);

  _________________________

  get : (A --> B --> unit);)

bw

Mark

[Mark Tarver]

Sorry - forgot put and get are macro driven - try.

(datatype properties

  X : A; Y : B; Z : C;

  ____________________________

  (put X Y Z (value *property-vector*)) : C;

  X : A; Y : B;

  _____________

  (get X Y (value *property-vector*)) : unit;)

Mark

  

  

Mark

[Mark Tarver]

BTW follow Bruno's advice - (spy +) is the best way to view the cogitations of the Shen type checker.

Mark