How to use quote and unquote to more faithfully translate The Reasoned Schemer into Racket?
(Details of my miniKanren in Racket setup appear at the bottom[1].)
The way quotes and unquotes work in The Reasoned Schemer appears not to match the way they work in Racket. For instance, verse 2 of chapter 2 suggests[2] the following function definition:
(run #f
(r )
(fresh (y x )
(== '(,x ,y) r )))
If I evaluate that, I get '((,x ,y)). If instead I rewrite it as this:
(run #f
(r )
(fresh (y x )
(== (list x y) r)))
I get the expected result, '((_.0 _.1)).
This might seem like a minor problem, but in many cases the required translation is extremely verbose. For instance, in exercise 45 of chapter 3 (page 34), the book provides, roughly[3] the following definition:
(run 5 (r)
(fresh (w x y z)
(loto (('g 'g) ('e w) (x y) . z))
(== (w (x y) z) r)))
In order to get the results they get, I had to rewrite it like this:
(run 5 (r)
(fresh (w x y z)
(loto (cons '(g g)
(cons (list 'e w)
(cons (list x y)
z))))
(== (list w (list x y) z)
r)))
[1] As described here, I ran raco pkg install minikanren and then defined a few missing pieces.
[2] Actually, they don't write precisely that, but if you heed the advice in the footnotes to that verse and an earlier verse, it's what you get.
[3] Modulo some implicit quoting and unquoting that I cannot deduce.
scheme racket quote minikanren
asked Nov 16 '18 at 3:35
Jeffrey Benjamin BrownJeffrey Benjamin Brown
9862923
|
show 4 more comments
(Details of my miniKanren in Racket setup appear at the bottom[1].)
The way quotes and unquotes work in The Reasoned Schemer appears not to match the way they work in Racket. For instance, verse 2 of chapter 2 suggests[2] the following function definition:
(run #f
(r )
(fresh (y x )
(== '(,x ,y) r )))
If I evaluate that, I get '((,x ,y)). If instead I rewrite it as this:
(run #f
(r )
(fresh (y x )
(== (list x y) r)))
I get the expected result, '((_.0 _.1)).
This might seem like a minor problem, but in many cases the required translation is extremely verbose. For instance, in exercise 45 of chapter 3 (page 34), the book provides, roughly[3] the following definition:
(run 5 (r)
(fresh (w x y z)
(loto (('g 'g) ('e w) (x y) . z))
(== (w (x y) z) r)))
In order to get the results they get, I had to rewrite it like this:
(run 5 (r)
(fresh (w x y z)
(loto (cons '(g g)
(cons (list 'e w)
(cons (list x y)
z))))
(== (list w (list x y) z)
r)))
[1] As described here, I ran raco pkg install minikanren and then defined a few missing pieces.
[2] Actually, they don't write precisely that, but if you heed the advice in the footnotes to that verse and an earlier verse, it's what you get.
[3] Modulo some implicit quoting and unquoting that I cannot deduce.
scheme racket quote minikanren
asked Nov 16 '18 at 3:35
Jeffrey Benjamin BrownJeffrey Benjamin Brown
9862923
4
Looks like you should usequasiquoteinstead ofquote.
– PetSerAl
Nov 16 '18 at 5:31
1
quasiquote is the one written with a backtick ( `` ` `` ) which is on the same key as tilde (~), not the normal tick (')
– Alex Knauth
Nov 16 '18 at 6:12
1
Also note that(cons '(g g) (cons (list 'e w) (cons (list x y) z)))can be written as(list* '(g g) (list 'e w) (list x y) z).
– PetSerAl
Nov 17 '18 at 18:32
1
@JeffreyBenjaminBrown Can you show example when this is not true? Assumingconsandlist*have their normal definitions, AFAIK,(list* a b c d e)should be the same as(cons a (cons b (cons c (cons d e)))). ideone.com/rxqmB5
– PetSerAl
Nov 17 '18 at 19:52
1
@JeffreyBenjaminBrown(list 1 3)is(1 3), but(list* 1 3)is(1 . 3).
– PetSerAl
Nov 17 '18 at 20:02
|
show 4 more comments
(Details of my miniKanren in Racket setup appear at the bottom[1].)
The way quotes and unquotes work in The Reasoned Schemer appears not to match the way they work in Racket. For instance, verse 2 of chapter 2 suggests[2] the following function definition:
(run #f
(r )
(fresh (y x )
(== '(,x ,y) r )))
If I evaluate that, I get '((,x ,y)). If instead I rewrite it as this:
(run #f
(r )
(fresh (y x )
(== (list x y) r)))
I get the expected result, '((_.0 _.1)).
This might seem like a minor problem, but in many cases the required translation is extremely verbose. For instance, in exercise 45 of chapter 3 (page 34), the book provides, roughly[3] the following definition:
(run 5 (r)
(fresh (w x y z)
(loto (('g 'g) ('e w) (x y) . z))
(== (w (x y) z) r)))
In order to get the results they get, I had to rewrite it like this:
(run 5 (r)
(fresh (w x y z)
(loto (cons '(g g)
(cons (list 'e w)
(cons (list x y)
z))))
(== (list w (list x y) z)
r)))
[1] As described here, I ran raco pkg install minikanren and then defined a few missing pieces.
[2] Actually, they don't write precisely that, but if you heed the advice in the footnotes to that verse and an earlier verse, it's what you get.
[3] Modulo some implicit quoting and unquoting that I cannot deduce.
scheme racket quote minikanren
asked Nov 16 '18 at 3:35
Jeffrey Benjamin BrownJeffrey Benjamin Brown
9862923
(Details of my miniKanren in Racket setup appear at the bottom[1].)
The way quotes and unquotes work in The Reasoned Schemer appears not to match the way they work in Racket. For instance, verse 2 of chapter 2 suggests[2] the following function definition:
(run #f
(r )
(fresh (y x )
(== '(,x ,y) r )))
If I evaluate that, I get '((,x ,y)). If instead I rewrite it as this:
(run #f
(r )
(fresh (y x )
(== (list x y) r)))
I get the expected result, '((_.0 _.1)).
This might seem like a minor problem, but in many cases the required translation is extremely verbose. For instance, in exercise 45 of chapter 3 (page 34), the book provides, roughly[3] the following definition:
(run 5 (r)
(fresh (w x y z)
(loto (('g 'g) ('e w) (x y) . z))
(== (w (x y) z) r)))
In order to get the results they get, I had to rewrite it like this:
(run 5 (r)
(fresh (w x y z)
(loto (cons '(g g)
(cons (list 'e w)
(cons (list x y)
z))))
(== (list w (list x y) z)
r)))
[1] As described here, I ran raco pkg install minikanren and then defined a few missing pieces.
[2] Actually, they don't write precisely that, but if you heed the advice in the footnotes to that verse and an earlier verse, it's what you get.
[3] Modulo some implicit quoting and unquoting that I cannot deduce.
scheme racket quote minikanren
scheme racket quote minikanren
asked Nov 16 '18 at 3:35
Jeffrey Benjamin BrownJeffrey Benjamin Brown
9862923
asked Nov 16 '18 at 3:35
Jeffrey Benjamin BrownJeffrey Benjamin Brown
9862923
edited Nov 16 '18 at 3:42
Jeffrey Benjamin Brown
asked Nov 16 '18 at 3:35
Jeffrey Benjamin BrownJeffrey Benjamin Brown
9862923
asked Nov 16 '18 at 3:35
Jeffrey Benjamin BrownJeffrey Benjamin Brown
9862923
asked Nov 16 '18 at 3:35
Jeffrey Benjamin BrownJeffrey Benjamin Brown
9862923
9862923
4
Looks like you should usequasiquoteinstead ofquote.
– PetSerAl
Nov 16 '18 at 5:31
1
quasiquote is the one written with a backtick ( `` ` `` ) which is on the same key as tilde (~), not the normal tick (')
– Alex Knauth
Nov 16 '18 at 6:12
1
Also note that(cons '(g g) (cons (list 'e w) (cons (list x y) z)))can be written as(list* '(g g) (list 'e w) (list x y) z).
– PetSerAl
Nov 17 '18 at 18:32
1
@JeffreyBenjaminBrown Can you show example when this is not true? Assumingconsandlist*have their normal definitions, AFAIK,(list* a b c d e)should be the same as(cons a (cons b (cons c (cons d e)))). ideone.com/rxqmB5
– PetSerAl
Nov 17 '18 at 19:52
1
@JeffreyBenjaminBrown(list 1 3)is(1 3), but(list* 1 3)is(1 . 3).
– PetSerAl
Nov 17 '18 at 20:02
|
show 4 more comments
4
Looks like you should usequasiquoteinstead ofquote.
– PetSerAl
Nov 16 '18 at 5:31
1
quasiquote is the one written with a backtick ( `` ` `` ) which is on the same key as tilde (~), not the normal tick (')
– Alex Knauth
Nov 16 '18 at 6:12
1
Also note that(cons '(g g) (cons (list 'e w) (cons (list x y) z)))can be written as(list* '(g g) (list 'e w) (list x y) z).
– PetSerAl
Nov 17 '18 at 18:32
1
@JeffreyBenjaminBrown Can you show example when this is not true? Assumingconsandlist*have their normal definitions, AFAIK,(list* a b c d e)should be the same as(cons a (cons b (cons c (cons d e)))). ideone.com/rxqmB5
– PetSerAl
Nov 17 '18 at 19:52
1
@JeffreyBenjaminBrown(list 1 3)is(1 3), but(list* 1 3)is(1 . 3).
– PetSerAl
Nov 17 '18 at 20:02
4
4
Looks like you should use
quasiquote instead of quote.– PetSerAl
Nov 16 '18 at 5:31
Looks like you should use
quasiquote instead of quote.– PetSerAl
Nov 16 '18 at 5:31
1
1
quasiquote is the one written with a backtick ( `` ` `` ) which is on the same key as tilde (
~), not the normal tick (')– Alex Knauth
Nov 16 '18 at 6:12
quasiquote is the one written with a backtick ( `` ` `` ) which is on the same key as tilde (
~), not the normal tick (')– Alex Knauth
Nov 16 '18 at 6:12
1
1
Also note that
(cons '(g g) (cons (list 'e w) (cons (list x y) z))) can be written as (list* '(g g) (list 'e w) (list x y) z).– PetSerAl
Nov 17 '18 at 18:32
Also note that
(cons '(g g) (cons (list 'e w) (cons (list x y) z))) can be written as (list* '(g g) (list 'e w) (list x y) z).– PetSerAl
Nov 17 '18 at 18:32
1
1
@JeffreyBenjaminBrown Can you show example when this is not true? Assuming
cons and list* have their normal definitions, AFAIK, (list* a b c d e) should be the same as (cons a (cons b (cons c (cons d e)))). ideone.com/rxqmB5– PetSerAl
Nov 17 '18 at 19:52
@JeffreyBenjaminBrown Can you show example when this is not true? Assuming
cons and list* have their normal definitions, AFAIK, (list* a b c d e) should be the same as (cons a (cons b (cons c (cons d e)))). ideone.com/rxqmB5– PetSerAl
Nov 17 '18 at 19:52
1
1
@JeffreyBenjaminBrown
(list 1 3) is (1 3), but (list* 1 3) is (1 . 3).– PetSerAl
Nov 17 '18 at 20:02
@JeffreyBenjaminBrown
(list 1 3) is (1 3), but (list* 1 3) is (1 . 3).– PetSerAl
Nov 17 '18 at 20:02
|
show 4 more comments
1 Answer
1
active
oldest
votes
Use the backquote ` instead of the simple quote ' you have been using.
answered Dec 3 '18 at 8:03
Will NessWill Ness
46.4k468126
add a comment |
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Use the backquote ` instead of the simple quote ' you have been using.
answered Dec 3 '18 at 8:03
Will NessWill Ness
46.4k468126
add a comment |
Use the backquote ` instead of the simple quote ' you have been using.
answered Dec 3 '18 at 8:03
Will NessWill Ness
46.4k468126
add a comment |
Use the backquote ` instead of the simple quote ' you have been using.
answered Dec 3 '18 at 8:03
Will NessWill Ness
46.4k468126
Use the backquote ` instead of the simple quote ' you have been using.
answered Dec 3 '18 at 8:03
Will NessWill Ness
46.4k468126
answered Dec 3 '18 at 8:03
Will NessWill Ness
46.4k468126
answered Dec 3 '18 at 8:03
Will NessWill Ness
46.4k468126
answered Dec 3 '18 at 8:03
Will NessWill Ness
46.4k468126
46.4k468126
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4
Looks like you should use
quasiquoteinstead ofquote.– PetSerAl
Nov 16 '18 at 5:31
1
quasiquote is the one written with a backtick ( `` ` `` ) which is on the same key as tilde (
~), not the normal tick (')– Alex Knauth
Nov 16 '18 at 6:12
1
Also note that
(cons '(g g) (cons (list 'e w) (cons (list x y) z)))can be written as(list* '(g g) (list 'e w) (list x y) z).– PetSerAl
Nov 17 '18 at 18:32
1
@JeffreyBenjaminBrown Can you show example when this is not true? Assuming
consandlist*have their normal definitions, AFAIK,(list* a b c d e)should be the same as(cons a (cons b (cons c (cons d e)))). ideone.com/rxqmB5– PetSerAl
Nov 17 '18 at 19:52
1
@JeffreyBenjaminBrown
(list 1 3)is(1 3), but(list* 1 3)is(1 . 3).– PetSerAl
Nov 17 '18 at 20:02