combining require, build-path, and namespaces

[Shriram Krishnamurthi]

How I can combine these three? I want to do something like this:

    (define n (make-base-namespace))

    (define p (build-path f))

    (eval `(require ,p) n)

Racket doesn't like that: bad syntax for require sub-form because p is a path-typed value.

Essentially, I want to inject the module at f into n so that the provided identifiers of f are visible inside n. (I haven't been able to get dynamic-require working either, nor is it an entirely satisfactory solution because I may not always know what names f is providing.)

Thanks,

Shriram

[Jens Axel Søgaard]

Sounds like a job for `namespace-require` with a require spec of the form `(file ,(path->string (build-path f)))`.

/Jens Axel

[Shriram Krishnamurthi]

Thank you! Would you know why I might get this error:

; require: unknown module

;   module name:

;     #<resolved-module-path: <<correct path name>>

(This is from inside a module.)

Trying the same at the REPL, I see the same thing:

> (define n (make-base-namespace))

> (namespace-require `(file ,(path->string (build-path "wheats" "w1.rkt"))))

[note no optional namespace]

works fine; the name is available at the top-level; but using the same pathname but with the namespace parameter:

> (namespace-require `(file ,(path->string (build-path "wheats" "w1.rkt"))) n)

; require: unknown module

;   module name:

;     #<resolved-module-path: <<correct path name>>

(The file in question begins with #lang racket.)

Shriram

[Sorawee Porncharoenwase]

This is weird. I usually parameterize current-namespace when using namespace-* functions, and in this particular case it works fine.

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[Jens Axel Søgaard]

Den tir. 21. jul. 2020 kl. 20.25 skrev Sorawee Porncharoenwase <sorawe...@gmail.com>:

This is weird. I usually parameterize current-namespace when using namespace-* functions, and in this particular case it works fine.

On Tue, Jul 21, 2020 at 11:05 AM Shriram Krishnamurthi <shr...@gmail.com> wrote:

Thank you! Would you know why I might get this error:

; require: unknown module

;   module name:

;     #<resolved-module-path: <<correct path name>>

(This is from inside a module.)

Trying the same at the REPL, I see the same thing:

> (define n (make-base-namespace))

> (namespace-require `(file ,(path->string (build-path "wheats" "w1.rkt"))))

[note no optional namespace]

works fine; the name is available at the top-level; but using the same pathname but with the namespace parameter:

> (namespace-require `(file ,(path->string (build-path "wheats" "w1.rkt"))) n)

; require: unknown module

;   module name:

;     #<resolved-module-path: <<correct path name>>

(The file in question begins with #lang racket.)

#lang racket

(define ns (make-base-namespace))
(define p  (build-path "/Users/soegaard/tmp" "w1.rkt"))

(parameterize ([current-namespace ns])
  (namespace-require p))

I had to dig up 

https://www.mail-archive.com/racket...@googlegroups.com/msg43291.html

to figure it out.

/Jens Axel

[Greg Hendershott]

Do you definitely want only definitions explicitly provide-ed by the module, or is it acceptable (or even desirable) to see all module definitions?  If the latter, you could use module->namespace.

[Shriram Krishnamurthi]

Ooh, thank you Oak and Jens Axel! I would never have figured that out.

As Matthew's email from Jan 2020 says, having the documentation say something (and, in particular, suggesting the use of `parameterize` to get what many users might expect) would be quite lovely.

(Thanks also, Greg.)

Shriram