Hi Thomas: you may wish to use errortrace to get more source locations
for error messages. It is enabled by default in DrRacket, but you have
to load it explicitly when you are working with the command-line
racket. Probably racket-mode has some support for it too, but I'm not
sure if it is turned on automatically there or not.
It isn't turned on by default for command-line racket because of the
fairly substantial performance penalty. But it isn't too bad if you
are just looking for a source location.
Here is an example of how one might use it.
☕ racket ~/tmp.rkt
<: contract violation
expected: real?
given: '(2 3)
argument position: 1st
other arguments...:
'(1 2)
context...:
/Users/robby/git/plt/racket/collects/racket/private/sort.rkt:213:0: sort
/Users/robby/tmp.rkt:2:0: f
/Users/robby/tmp.rkt: [running body]
☕ [robby@gongguan] ~
☕ racket -l errortrace -t ~/tmp.rkt
<: contract violation
expected: real?
given: '(2 3)
argument position: 1st
other arguments...:
'(1 2)
errortrace...:
/Users/robby/git/plt/racket/collects/racket/private/kw.rkt:1114:47:
(sort7 (quote #f) (quote #f) (quote #f) (quote #f) temp1 <2)
/Users/robby/tmp.rkt:3:2: (reverse (sort (quote ((1 2) (2 3) (3 ....))) <))
/Users/robby/tmp.rkt:7:0: (f 11)
context...:
/Users/robby/git/plt/racket/collects/racket/private/sort.rkt:213:0: sort
/Users/robby/tmp.rkt:2:0: f
/Users/robby/tmp.rkt: [running body]
☕ [robby@gongguan] ~
☕
☕ [robby@gongguan] ~
☕ cat ~/tmp.rkt
#lang racket
(define (f x)
(reverse
(sort '((1 2) (2 3) (3 4))
<)))
(f 11)
Robby
On Fri, Oct 30, 2015 at 1:34 AM, Thomas Lynch
<[email protected]> wrote:
> These are exemplar problematical error messages from racket. If messages
> like these were more specific it would save a lot of developer's time. All
> of these have been solved, rather this is just feedback to developers.
>
> 1. this was hard to locate
>
> [email protected]> (enter! "db-lib.rkt")
> db-lib-init: unbound identifier in module
> in: db-lib-init
> context...:
> standard-module-name-resolver
> /usr/share/racket/collects/racket/rerequire.rkt:18:0: rerequire
> /usr/share/racket/collects/racket/enter.rkt:54:0: dynamic-enter!6
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
>
> 2. went away after running raco setup, but curious as to which variable was
> the problem
>
> [email protected]> (enter! "ap.rkt")
> [re-loading /home/deep/liquid-examples/test-ap/ap.rkt]
> link: bad variable linkage;
> reference to a variable that is not a procedure or structure-type constant
> across all instantiations
> reference phase level: 0
> variable module: "/home/deep/liquid-lib/liquid/misc-lib.rkt"
> variable phase: 0
> reference in module: "/home/deep/liquid-lib/liquid/http-session.rkt"
> in: session-context-out
> context...:
> /home/deep/liquid-lib/liquid/http-session.rkt: [running body]
> /home/deep/liquid-examples/test-ap/ap.rkt: [traversing imports]
> /usr/share/racket/collects/racket/enter.rkt:54:0: dynamic-enter!6
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
>
> 3. obj:set! is a commonly used method in this code, would be nice to know
> which invocation.
>
> [email protected]> (enter! "node.rkt")
> obj:set!: arity mismatch;
> the expected number of arguments does not match the given number
> expected: 3
> given: 4
> arguments...:
> 0
> 9
> 'field:debug
> "nd:type"
> context...:
> /home/deep/liquid-lib/liquid/node.rkt: [running body]
> /usr/share/racket/collects/racket/rerequire.rkt:18:0: rerequire
> /usr/share/racket/collects/racket/enter.rkt:54:0: dynamic-enter!6
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
>
> 4. liquid.scrbl is the top file that includes all the sections..
>
>
> §lambda1:/home/deep/liquid-doc/liquid> raco setup --pkgs liquid-doc
> raco setup: version: 6.1 [3m]
> raco setup: installation name: 6.1
> raco setup: variants: 3m
> raco setup: main collects: /usr/share/racket/collects
> raco setup: collects paths:
> raco setup: /home/mordecai/.racket/6.1/collects
> raco setup: /usr/share/racket/collects
> raco setup: main pkgs: /usr/share/racket/pkgs
> raco setup: pkgs paths:
> raco setup: /usr/share/racket/pkgs
> raco setup: /home/mordecai/.racket/6.1/pkgs
> raco setup: links files:
> raco setup: /usr/share/racket/links.rktd
> raco setup: /home/mordecai/.racket/6.1/links.rktd
> raco setup: main docs: /usr/share/doc/racket
> raco setup: --- updating info-domain tables ---
> raco setup: --- pre-installing collections ---
> raco setup: --- installing foreign libraries ---
> raco setup: --- installing shared files ---
> raco setup: --- compiling collections ---
> raco setup: --- parallel build using 2 jobs ---
> raco setup: 1 making: <pkgs>/liquid-doc/compiled
> raco setup: 1 making: <pkgs>/liquid-doc/liquid
> raco setup: --- creating launchers ---
> raco setup: --- installing man pages ---
> raco setup: --- building documentation ---
> raco setup: 1 running: <pkgs>/liquid-doc/liquid/liquid.scrbl
> prog:3:0: read: expected a `)' to close `('
> possible cause: indentation suggests a missing `)' before line 7
> context...:
>
> /usr/share/racket/pkgs/scribble-lib/scribble/private/manual-code.rkt:56:0:
> typeset-code15
>
> /home/deep/liquid-doc/liquid/multiple-continuations-architecture.scrbl:
> [running body]
> /home/deep/liquid-doc/liquid/architecture.scrbl: [traversing
> imports]
> /home/deep/liquid-doc/liquid/liquid.scrbl: [traversing imports]
> /usr/share/racket/pkgs/racket-index/setup/scribble.rkt:895:0:
> load-doc/ensure-prefix
> /usr/share/racket/pkgs/racket-index/setup/scribble.rkt:1146:13
> /usr/share/racket/collects/setup/parallel-do.rkt:420:20: loop
>
> Turns out that it isn't in liquid.scrbl, it is in two include files down.
> It is not
> on line 7, but was well into the file, and it wasn't part of the document
> structure, but
> it was in a quoted example .. in
> multiple-continuations-architecture.scrbl:
>
> #lang scribble/manual
> @(require (for-label racket/base
> ))
>
> @title[#:style '(toc)]{Multiple Continuations Architecture}
>
> @section{The Basic Approach}
>
> As a matter of convention, we simplify function calls by not using
> variable arguments, but
> instead where variable arguments are required we use explicit lists.
> We make this more
> convenient by introducing the Unicode capital lambda, Λ, as a synonym
> for @racket[list].
> In Emacs I have added both λ and Λ to my key map as alt-l and
> alt-shift-l.
>
> Our basic approach is to pass continuation functions as arguments. By
> convention the
> first function is the 'normal flow'. By convention we call the first
> function
> continuation-ok. For example, this is the definition for an extended
> hash ref that takes
> continuation functions. It is implemented as a wrapper. Of course it
> would be better to
> have a native version.
>
> ...
>
>
> @codeblock|{
> ...
> (define a 7)
> (x-hash-ref table a
> (λ(v) (display "found: ")(displayln v))
> (λ() (displayln "did not find 7 ") <--- scrble is mad this
> isn't balanced
> )
> ...
> }|
>
> 5. ended up having to write a lot of special code for debugging this, the
> bug was not in
> obj:add-type as indicated in the message, and certainly not on line 141.
>
> racket@> (enter! "object.rkt")
> ...
> (0.type-type)
> (obj:has-type 0 0)
> application: not a procedure;
> expected a procedure that can be applied to arguments
> given: 302
> arguments...:
> 4
> context...:
> x-hash-ref
> /home/deep/liquid-lib/liquid/object.rkt:141:4: obj:add-type
> /home/deep/liquid-lib/liquid/object.rkt: [running body]
> /usr/share/racket/collects/racket/rerequire.rkt:18:0: rerequire
> /usr/share/racket/collects/racket/enter.rkt:54:0: dynamic-enter!6
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
>
> 6. but where?
>
> [email protected]> (obj-test-1)
> =: contract violation
> expected: number?
> given: #f
> argument position: 1st
> other arguments...:
> 12
> context...:
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
>
>
> 7. oh the cruelty of it! ;-)
>
> "object.rkt"> (obj-test-1)
> (4.type:summable)
> (5.test-1-obj1)
> (6.test-1-obj2)
> (args type:summable + (test-1-obj1 test-1-obj2))
> (conts #<procedure> #<procedure> #<procedure>)
> (## at (/home/deep/liquid-lib/liquid/object.rkt 221 4))
> (-- expected length of 3 )
> (-- for: (#<procedure>))
> ; uncaught exception: 'exception:check [,bt for context]
> "object.rkt"> ,bt
> ; uncaught exception: 'exception:check
> "object.rkt">
>
>
> 8. you might think that a person could just look for the first summable in
> the module,
> but no, as that one is well defined. so I have to search for all 'summable'
> .. why
> doesn't the compiler tell me which one?
>
>
> [email protected]> (enter! "object.rkt")
> [re-loading /home/deep/liquid-lib/liquid/object.rkt]
> summable: unbound identifier in module
> in: summable
> context...:
> /usr/share/racket/collects/racket/enter.rkt:54:0: dynamic-enter!6
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
>
>
> 9. racket reports arity error, but does not say for which function ...
> (turns out to be in obj:set! which I found
> by walking through a trace). line 421, which it cites, is simply the line
> of the define (obj-test-2) ...
>
> [email protected]> (obj-test-2)
> >(obj:make "type:summable")
> (47.type:summable)
> <47
> >(obj:make "test-2-obj1")
> (48.test-2-obj1)
> <48
> >(obj:make "test-2-obj2")
> (49.test-2-obj2)
> <49
> >(obj:add-type 48 47)
> > (obj:is 47)
> < #t
> > (obj:is 48)
> < #t
> > (obj:has-type 48 47)
> > >(obj:is 47)
> < <#t
> > (x-hash-ref
> '(#hasheq((47 . #hasheqv())
> (46 . #hasheqv((46 . #hasheqv())))
> (49 . #hasheqv())
> (48 . #hasheqv()))
> 48)
> '(#<procedure> #<procedure>))
> > >(be #t)
> < <#<procedure:beit>
> > >(be #f)
> < <#<procedure:beit>
> > (x-hash-ref '(#hasheqv() 47) '(#<procedure:beit> #<procedure:beit>))
> < #f
> > (x-hash-ref
> '(#hasheq((47 . #hasheqv())
> (46 . #hasheqv((46 . #hasheqv())))
> (49 . #hasheqv())
> (48 . #hasheqv()))
> 48)
> '(#<procedure> #<procedure>))
> < #<void>
> <48
> >(obj:add-type 49 47)
> > (obj:is 47)
> < #t
> > (obj:is 49)
> < #t
> > (obj:has-type 49 47)
> > >(obj:is 47)
> < <#t
> > (x-hash-ref
> '(#hasheq((47 . #hasheqv())
> (46 . #hasheqv((46 . #hasheqv())))
> (49 . #hasheqv())
> (48 . #hasheqv((47 . #hasheqv()))))
> 49)
> '(#<procedure> #<procedure>))
> > >(be #t)
> < <#<procedure:beit>
> > >(be #f)
> < <#<procedure:beit>
> > (x-hash-ref '(#hasheqv() 47) '(#<procedure:beit> #<procedure:beit>))
> < #f
> > (x-hash-ref
> '(#hasheq((47 . #hasheqv())
> (46 . #hasheqv((46 . #hasheqv())))
> (49 . #hasheqv())
> (48 . #hasheqv((47 . #hasheqv()))))
> 49)
> '(#<procedure> #<procedure>))
> < #<void>
> <49
> #<procedure>: arity mismatch;
> the expected number of arguments does not match the given number
> expected: 2
> given: 3
> arguments...:
> 47
> 49
> '(x 21)
> context...:
> /home/deep/liquid-lib/liquid/object.rkt:421:0: obj-test-2
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
> [email protected]>
>
> 10.
>
> [email protected]> (with-db (current-example-db) (db:alloc-name))
> lifted.0.3: undefined;
> cannot reference an identifier before its definition
> in module: "/home/deep/liquid-lib/liquid/kw.rkt"
> context...:
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
>
>
> §lambda1:/home/deep/liquid-lib/liquid> grep lifted *.rkt
>
> §lambda1:/home/deep/liquid-lib/liquid>
>
>
> 11.
>
> [email protected]> (enter! "kw.rkt")
> [re-loading /home/deep/liquid-lib/liquid/kw.rkt]
> _: wildcard not allowed as an expression
> in: _
> [email protected]>
>
>
> 12. doesn't tell which function the error came from, nor give a source line
> number
>
> line 851 is the entry point (semantic-relation:lookup-ids-test-1) ,
> which doesn't
> take arguments, sort is called in multiple places ... which one?
>
> [email protected]> (semantic-relation:lookup-ids-test-1)
> <: contract violation
> expected: real?
> given: '(1 4 7 10)
> argument position: 1st
> other arguments...:
> '(1 7 10)
> context...:
> /usr/share/racket/collects/racket/private/sort.rkt:213:0: sort
> /home/deep/liquid-lib/liquid/dataplex-lib.rkt:851:4:
> semantic-relation:lookup-ids-test-1
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
> [email protected]>
>
> 13. error is where in the function?
>
> [email protected]> (define (display-sm an-sm)
> (with-db (current-example-db)
> (let*(
> [t0 (semantic-relation:match dp-ex1 R1 '_)] ; returns a
> list of rows, each row item is a singleton sp value
> [t1 (map (λ(row)(map (λ(item)(car item)) row)) t0)] ;
> strips parens off of the singleton row items
> )
> (map (λ(row)displayln(row)) t1) ;; <----- error on this line
> )))
>
> [email protected]> (display-sm R1)
> application: not a procedure;
> expected a procedure that can be applied to arguments
> given: '("k1" "c1")
> arguments...: [none]
> context...:
> stdin::739: display-sm
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
> [email protected]> display-sm
> #<procedure:display-sm>
>
>
> and tried at the prompt, the error goes away:
>
> [email protected]> (define (display-sm an-sm)
> (with-db (current-example-db)
> (let*(
> [t0 (semantic-relation:match dp-ex1 R1 '_)] ; returns a
> list of rows, each row item is a singleton sp value
> ;; [t1 (map (λ(row)(map (λ(item)(car item)) row)) t0)] ;
> strips parens off of the singleton row items
> [t1 '()]
> )
> (map (λ(row)displayln(row)) t1)
> )))
> [email protected]> (display-sm R1)
> '()
> [email protected]> t0
> '((("k1") ("c1")) (("c2") ("c3")))
> [email protected]> (map (λ(row)(map (λ(item)(car item)) row)) t0)
> '(("k1" "c1") ("c2" "c3"))
> [email protected]> (define t1 (map (λ(row)(map (λ(item)(car item)) row))
> t0))
>
>
> 14. this identifier dosn't appear in this file ... if it is created by a
> macro, then which macro? which invocation of the macro?
>
> Process Racket REPL finished
> Welcome to Racket v6.1.
> racket@> (enter! "kw.rkt")
> shape-relation:values:index-by-sp-id: unbound identifier in module
> in: shape-relation:values:index-by-sp-id
> racket@>
>
> 15. turned out to be code generated by a syntax transformer, sure would have
> been helpful to have been
> told where it was called from, which macro, and where in the macro ...
>
> racket@> (enter! "extentions-lib.rkt")
> when: bad syntax
> in: (when else-flag)
> context...:
> standard-module-name-resolver
> /usr/share/racket/collects/racket/rerequire.rkt:18:0: rerequire
> /usr/share/racket/collects/racket/enter.rkt:54:0: dynamic-enter!6
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
> racket@>
>
>
> 16. ok ... so there is an error somewhere in the module having to do with
> redefining test-Λ-0
>
>
> [email protected]> (enter! "sequence-lib.rkt")
> [re-loading /home/deep/liquid-lib/liquid/sequence-lib.rkt]
> (wrap test: #f)
> (wrap test: #f)
> (wrap test: #f)
> hooking test: test-unwrap
> define-values: assignment disallowed;
> cannot re-define a constant
> constant: test-Λ-0
> in module: "/home/deep/liquid-lib/liquid/sequence-lib.rkt"
> context...:
> /home/deep/liquid-lib/liquid/sequence-lib.rkt: [running body]
> /usr/share/racket/collects/racket/enter.rkt:54:0: dynamic-enter!6
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
>
>
> problem is, this is the only occurance of that identifier in the module:
>
> ;; does the job of list
> (define (test-Λ-0)
> (equal? '(1 2 3) (Λ 1 2 3))
> )
> (test-hook test-Λ-0)
>
> 17. error is somewhere in extensions-lib.rkt, presumably in one of the many
> wrap calls,
> will trace wrap .. oh, can't do that as this fails on load .. line 157 in
> sequence-lib
> and is first line of wrap, so there is no hint as to where in wrap this
> problem occurs (or
> where wrap was called from).
>
>
> [email protected]> (enter! "extentions-lib.rkt")
> [re-loading /home/deep/liquid-lib/liquid/extentions-lib.rkt]
> cdr: contract violation
> expected: pair?
> given: 'Λ
> context...:
> /home/deep/liquid-lib/liquid/sequence-lib.rkt:157:2
> /usr/share/racket/collects/racket/enter.rkt:54:0: dynamic-enter!6
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
>
> ... problem turned out to be in the cond/list program in extentions-lib.rkt,
> (define seq-op Λ) was supposed
> to be (define seq-op 'Λ). found by stubbing out the program and bring
> pieces to life one by one.
>
> 18. Not sure how we are supposed to know that this error occurs in
> http-server.rkt, as the
> top of the trace is the name of a macro in test lib. Perhaps because it
> was the
> module loaded? When finding the top of the trace, we discover in
> http-server.rkt,
> that the macro is only called once, so that narrows it down. In other
> examples, a
> simple macro can be used many times. Solving these is a real mystery
> thriller because
> it bombs on load, so you can't set traces.
>
> racket@> (enter! "http-server.rkt")
> string-append: contract violation
> expected: string?
> given: 'server-pages-init
> argument position: 1st
> other arguments...:
> "-trace"
> context...:
> /home/deep/liquid-extensions/liquid/test-lib.rkt:121:2
> /usr/share/racket/collects/syntax/wrap-modbeg.rkt:46:4
> standard-module-name-resolver
> standard-module-name-resolver
> /usr/share/racket/collects/racket/rerequire.rkt:18:0: rerequire
> /usr/share/racket/collects/racket/enter.rkt:54:0: dynamic-enter!6
> /usr/share/racket/collects/racket/private/misc.rkt:87:7
> racket@>
>
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