diff --git a/guix/import/cran.scm b/guix/import/cran.scm
index bb271634ed..d25f334396 100644
--- a/guix/import/cran.scm
+++ b/guix/import/cran.scm
@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2015-2023 Ricardo Wurmus <rekado@elephly.net>
-;;; Copyright © 2015, 2016, 2017, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015-2017, 2019-2021, 2023 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2020 Martin Becze <mjbecze@riseup.net>
 ;;; Copyright © 2021 Sarah Morgensen <iskarian@mgsn.dev>
@@ -164,24 +164,16 @@ (define (description->alist description)
                                  rest)))))))
     (fold parse '() lines)))
 
-(define (format-inputs names)
-  "Generate a sorted list of package inputs from a list of package NAMES."
-  (map (lambda (name)
-         (case (%input-style)
-           ((specification)
-            `(specification->package ,name))
-           (else
-            (string->symbol name))))
-       (sort names string-ci<?)))
-
-(define* (maybe-inputs package-inputs #:optional (type 'inputs))
+(define* (maybe-inputs package-inputs #:optional (input-type 'inputs))
   "Given a list of PACKAGE-INPUTS, tries to generate the TYPE field of a
 package definition."
   (match package-inputs
     (()
      '())
     ((package-inputs ...)
-     `((,type (list ,@(format-inputs package-inputs)))))))
+     `((,input-type (list ,@(map (compose string->symbol
+                                          upstream-input-downstream-name)
+                                 package-inputs)))))))
 
 (define %cran-url "https://cran.r-project.org/web/packages/")
 (define %cran-canonical-url "https://cran.r-project.org/package=")
@@ -520,14 +512,29 @@ (define (directory-needs-pkg-config? dir)
                         "(Makevars.*|configure.*)"))
 
 (define (source-dir->dependencies dir)
-  "Guess dependencies of R package source in DIR and return two values: a list
-of package names for INPUTS and another list of names of NATIVE-INPUTS."
-  (values
-   (needed-libraries-in-directory dir)
-   (append
-       (if (directory-needs-esbuild? dir) '("esbuild") '())
-       (if (directory-needs-pkg-config? dir) '("pkg-config") '())
-       (if (directory-needs-fortran? dir) '("gfortran") '()))))
+  "Guess dependencies of R package source in DIR and return a list of
+<upstream-input> corresponding to the dependencies guessed from source files
+in DIR."
+  (define (native name)
+    (upstream-input
+     (name name)
+     (downstream-name name)
+     (type 'native)))
+
+  (append (map (lambda (name)
+                 (upstream-input
+                  (name name)
+                  (downstream-name (cran-guix-name name))))
+               (needed-libraries-in-directory dir))
+          (if (directory-needs-esbuild? dir)
+              (list (native "esbuild"))
+              '())
+          (if (directory-needs-pkg-config? dir)
+              (list (native "pkg-config"))
+              '())
+          (if (directory-needs-fortran? dir)
+              (list (native "gfortran"))
+              '())))
 
 (define (source->dependencies source tarball?)
   "SOURCE-DIR->DEPENDENCIES, but for directories and tarballs as indicated
@@ -541,7 +548,79 @@ (define (source->dependencies source tarball?)
     (source-dir->dependencies source)))
 
 (define (vignette-builders meta)
-  (map cran-guix-name (listify meta "VignetteBuilder")))
+  (map (lambda (name)
+         (upstream-input
+          (name name)
+          (downstream-name (cran-guix-name name))
+          (type 'native)))
+       (listify meta "VignetteBuilder")))
+
+(define (uri-helper repository)
+  (match repository
+    ('cran         cran-uri)
+    ('bioconductor bioconductor-uri)
+    ('git          #f)
+    ('hg           #f)))
+
+(define (cran-package-source-url meta repository)
+  "Return the URL of the source code referred to by META, a package in
+REPOSITORY."
+  (case repository
+    ((git) (assoc-ref meta 'git))
+    ((hg)  (assoc-ref meta 'hg))
+    (else
+     (match (apply (uri-helper repository)
+                   (assoc-ref meta "Package")
+                   (assoc-ref meta "Version")
+                   (case repository
+                     ((bioconductor)
+                      (list (assoc-ref meta 'bioconductor-type)))
+                     (else '())))
+       ((urls ...) urls)
+       ((? string? url) url)
+       (_ #f)))))
+
+(define (cran-package-propagated-inputs meta)
+  "Return the list of <upstream-input> derived from dependency information in
+META."
+  (filter-map (lambda (name)
+                (and (not (member name
+                                  (append default-r-packages invalid-packages)))
+                     (upstream-input
+                      (name name)
+                      (downstream-name (cran-guix-name name))
+                      (type 'propagated))))
+              (lset-union equal?
+                          (listify meta "Imports")
+                          (listify meta "LinkingTo")
+                          (delete "R" (listify meta "Depends")))))
+
+(define* (cran-package-inputs meta repository
+                              #:key (download-source download))
+  "Return the list of <upstream-input> corresponding to all the dependencies
+of META, a package in REPOSITORY."
+  (let* ((url    (cran-package-source-url meta repository))
+         (source (download-source url
+                                  #:method
+                                  (cond ((assoc-ref meta 'git) 'git)
+                                        ((assoc-ref meta 'hg) 'hg)
+                                        (else #f))))
+         (tarball? (not (or (assoc-ref meta 'git)
+                            (assoc-ref meta 'hg)))))
+    (sort (append (source->dependencies source tarball?)
+                  (filter-map (lambda (name)
+                                (and (not (member name invalid-packages))
+                                     (upstream-input
+                                      (name name)
+                                      (downstream-name
+                                       (transform-sysname name)))))
+                              (map string-downcase
+                                   (listify meta "SystemRequirements")))
+                  (cran-package-propagated-inputs meta)
+                  (vignette-builders meta))
+          (lambda (input1 input2)
+            (string<? (upstream-input-downstream-name input1)
+                      (upstream-input-downstream-name input2))))))
 
 (define* (description->package repository meta #:key (license-prefix identity)
                                (download-source download))
@@ -556,11 +635,6 @@ (define* (description->package repository meta #:key (license-prefix identity)
                                ((cran)         %cran-canonical-url)
                                ((bioconductor) %bioconductor-url)
                                ((git)          #f)))
-         (uri-helper (case repository
-                       ((cran)         cran-uri)
-                       ((bioconductor) bioconductor-uri)
-                       ((git)          #f)
-                       ((hg)           #f)))
          (name       (assoc-ref meta "Package"))
          (synopsis   (assoc-ref meta "Title"))
          (version    (assoc-ref meta "Version"))
@@ -572,40 +646,16 @@ (define* (description->package repository meta #:key (license-prefix identity)
                        (else (match (listify meta "URL")
                                ((url rest ...) url)
                                (_ (string-append canonical-url-base name))))))
-         (source-url (case repository
-                       ((git) (assoc-ref meta 'git))
-                       ((hg)  (assoc-ref meta 'hg))
-                       (else
-                        (match (apply uri-helper name version
-                                      (case repository
-                                        ((bioconductor)
-                                         (list (assoc-ref meta 'bioconductor-type)))
-                                        (else '())))
-                          ((urls ...) urls)
-                          ((? string? url) url)
-                          (_ #f)))))
+         (source-url (cran-package-source-url meta repository))
          (git?       (if (assoc-ref meta 'git) #true #false))
          (hg?        (if (assoc-ref meta 'hg) #true #false))
          (source     (download-source source-url #:method (cond
                                                            (git? 'git)
                                                            (hg? 'hg)
                                                            (else #f))))
-         (tarball?   (not (or git? hg?)))
-         (source-inputs source-native-inputs
-          (source->dependencies source tarball?))
-         (sysdepends (append
-                      source-inputs
-                      (filter (lambda (name)
-                                (not (member name invalid-packages)))
-                              (map string-downcase (listify meta "SystemRequirements")))))
-         (propagate  (filter (lambda (name)
-                               (not (member name (append default-r-packages
-                                                         invalid-packages))))
-                             (lset-union equal?
-                                         (listify meta "Imports")
-                                         (listify meta "LinkingTo")
-                                         (delete "R"
-                                                 (listify meta "Depends")))))
+         (uri-helper (uri-helper repository))
+         (inputs     (cran-package-inputs meta repository
+                                          #:download-source download-source))
          (package
            `(package
               (name ,(cran-guix-name name))
@@ -651,12 +701,18 @@ (define* (description->package repository meta #:key (license-prefix identity)
                     `((properties ,`(,'quasiquote ((,'upstream-name . ,name)))))
                     '())
               (build-system r-build-system)
-              ,@(maybe-inputs (map transform-sysname sysdepends))
-              ,@(maybe-inputs (map cran-guix-name propagate) 'propagated-inputs)
-              ,@(maybe-inputs
-                 `(,@source-native-inputs
-                   ,@(vignette-builders meta))
-                 'native-inputs)
+
+              ,@(maybe-inputs (filter (upstream-input-type-predicate 'regular)
+                                      inputs)
+                              'inputs)
+              ,@(maybe-inputs (filter (upstream-input-type-predicate
+                                       'propagated)
+                                      inputs)
+                              'propagated-inputs)
+              ,@(maybe-inputs (filter (upstream-input-type-predicate 'native)
+                                      inputs)
+                              'native-inputs)
+
               (home-page ,(if (string-null? home-page)
                               (string-append base-url name)
                               home-page))
@@ -675,7 +731,10 @@ (define* (description->package repository meta #:key (license-prefix identity)
               (revision "1"))
           ,package))
       (else package))
-     propagate)))
+     (filter-map (lambda (input)
+                   (and (eq? 'propagated (upstream-input-type input))
+                        (upstream-input-name input)))
+                 inputs))))
 
 (define cran->guix-package
   (memoize
@@ -760,9 +819,7 @@ (define* (latest-cran-release pkg #:key (version #f))
           (package (package-name pkg))
           (version version)
           (urls (cran-uri upstream-name version))
-          (input-changes
-           (changed-inputs pkg
-                           (description->package 'cran meta)))))))
+          (inputs (cran-package-inputs meta 'cran))))))
 
 (define* (latest-bioconductor-release pkg #:key (version #f))
   "Return an <upstream-source> for the latest release of the package PKG."
@@ -784,10 +841,9 @@ (define* (latest-bioconductor-release pkg #:key (version #f))
         (package (package-name pkg))
         (version latest-version)
         (urls (bioconductor-uri upstream-name latest-version))
-        (input-changes
-         (changed-inputs
-          pkg
-          (cran->guix-package upstream-name #:repo 'bioconductor))))))
+        (inputs
+         (let ((meta (fetch-description 'bioconductor upstream-name)))
+           (cran-package-inputs meta 'bioconductor))))))
 
 (define (cran-package? package)
   "Return true if PACKAGE is an R package from CRAN."
diff --git a/guix/import/hackage.scm b/guix/import/hackage.scm
index 56c8696ad7..9333bedbbd 100644
--- a/guix/import/hackage.scm
+++ b/guix/import/hackage.scm
@@ -8,6 +8,7 @@
 ;;; Copyright © 2021 Sarah Morgensen <iskarian@mgsn.dev>
 ;;; Copyright © 2019 Simon Tournier <zimon.toutoune@gmail.com>
 ;;; Copyright © 2022 Hartmut Goebel <h.goebel@crazy-compilers.com>
+;;; Copyright © 2023 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -56,7 +57,9 @@ (define-module (guix import hackage)
             hackage-fetch
             hackage-source-url
             hackage-cabal-url
-            hackage-package?))
+            hackage-package?
+
+            cabal-package-inputs))
 
 (define ghc-standard-libraries
   ;; List of libraries distributed with ghc (as of 8.10.7).
@@ -224,27 +227,12 @@ (define (filter-dependencies dependencies own-names)
     (filter (lambda (d) (not (member (string-downcase d) ignored-dependencies)))
             dependencies)))
 
-(define* (hackage-module->sexp cabal cabal-hash
-                               #:key (include-test-dependencies? #t))
-  "Return the `package' S-expression for a Cabal package.  CABAL is the
-representation of a Cabal file as produced by 'read-cabal'.  CABAL-HASH is
-the hash of the Cabal file."
-
-  (define name
-    (cabal-package-name cabal))
-
-  (define version
-    (cabal-package-version cabal))
-
-  (define revision
-    (cabal-package-revision cabal))
-  
-  (define source-url
-    (hackage-source-url name version))
-
-  (define own-names (cons (cabal-package-name cabal)
-                          (filter (lambda (x) (not (eqv? x #f)))
-                            (map cabal-library-name (cabal-package-library cabal)))))
+(define* (cabal-package-inputs cabal #:key (include-test-dependencies? #t))
+  "Return the list of <upstream-input> for CABAL representing its
+dependencies."
+  (define own-names
+    (cons (cabal-package-name cabal)
+          (filter-map cabal-library-name (cabal-package-library cabal))))
 
   (define hackage-dependencies
     (filter-dependencies (cabal-dependencies->names cabal) own-names))
@@ -261,22 +249,54 @@ (define* (hackage-module->sexp cabal cabal-hash
      hackage-dependencies))
 
   (define dependencies
-    (map string->symbol
-         (map hackage-name->package-name
-              hackage-dependencies)))
+    (map (lambda (name)
+           (upstream-input
+            (name name)
+            (downstream-name (hackage-name->package-name name))
+            (type 'regular)))
+         hackage-dependencies))
 
   (define native-dependencies
-    (map string->symbol
-         (map hackage-name->package-name
-              hackage-native-dependencies)))
-  
+    (map (lambda (name)
+           (upstream-input
+            (name name)
+            (downstream-name (hackage-name->package-name name))
+            (type 'native)))
+         hackage-native-dependencies))
+
+  (append dependencies native-dependencies))
+
+(define* (hackage-module->sexp cabal cabal-hash
+                               #:key (include-test-dependencies? #t))
+  "Return the `package' S-expression for a Cabal package.  CABAL is the
+representation of a Cabal file as produced by 'read-cabal'.  CABAL-HASH is
+the hash of the Cabal file."
+  (define name
+    (cabal-package-name cabal))
+
+  (define version
+    (cabal-package-version cabal))
+
+  (define revision
+    (cabal-package-revision cabal))
+
+  (define source-url
+    (hackage-source-url name version))
+
+  (define inputs
+    (cabal-package-inputs cabal
+                          #:include-test-dependencies?
+                          include-test-dependencies?))
+
   (define (maybe-inputs input-type inputs)
     (match inputs
       (()
        '())
       ((inputs ...)
        (list (list input-type
-                   `(list ,@inputs))))))
+                   `(list ,@(map (compose string->symbol
+                                          upstream-input-downstream-name)
+                                 inputs)))))))
 
   (define (maybe-arguments)
     (match (append (if (not include-test-dependencies?)
@@ -304,14 +324,18 @@ (define* (hackage-module->sexp cabal cabal-hash
                          "failed to download tar archive")))))
         (build-system haskell-build-system)
         (properties '((upstream-name . ,name)))
-        ,@(maybe-inputs 'inputs dependencies)
-        ,@(maybe-inputs 'native-inputs native-dependencies)
+        ,@(maybe-inputs 'inputs
+                        (filter (upstream-input-type-predicate 'regular)
+                                inputs))
+        ,@(maybe-inputs 'native-inputs
+                        (filter (upstream-input-type-predicate 'native)
+                                inputs))
         ,@(maybe-arguments)
         (home-page ,(cabal-package-home-page cabal))
         (synopsis ,(cabal-package-synopsis cabal))
         (description ,(beautify-description (cabal-package-description cabal)))
         (license ,(string->license (cabal-package-license cabal))))
-     (append hackage-dependencies hackage-native-dependencies))))
+     inputs)))
 
 (define* (hackage->guix-package package-name #:key
                                 (include-test-dependencies? #t)
diff --git a/guix/import/pypi.scm b/guix/import/pypi.scm
index 8c06b19cff..1a3070fb36 100644
--- a/guix/import/pypi.scm
+++ b/guix/import/pypi.scm
@@ -1,7 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2014 David Thompson <davet@gnu.org>
 ;;; Copyright © 2015 Cyril Roelandt <tipecaml@gmail.com>
-;;; Copyright © 2015-2017, 2019-2022 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015-2017, 2019-2023 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;; Copyright © 2018, 2023 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2019 Maxim Cournoyer <maxim.cournoyer@gmail.com>
@@ -33,12 +33,16 @@
 (define-module (guix import pypi)
   #:use-module (ice-9 match)
   #:use-module (ice-9 regex)
-  #:use-module (ice-9 receive)
   #:use-module ((ice-9 rdelim) #:select (read-line))
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-34)
   #:use-module (srfi srfi-35)
+  #:use-module (srfi srfi-71)
+  #:autoload   (gcrypt hash) (port-sha256)
+  #:autoload   (guix base16) (base16-string->bytevector)
+  #:autoload   (guix base32) (bytevector->nix-base32-string)
+  #:autoload   (guix http-client) (http-fetch)
   #:use-module (guix utils)
   #:use-module (guix memoization)
   #:use-module (guix diagnostics)
@@ -126,6 +130,12 @@ (define-json-mapping <distribution> make-distribution distribution?
   (python-version distribution-package-python-version
                   "python_version"))
 
+(define (distribution-sha256 distribution)
+  "Return the SHA256 hash of DISTRIBUTION as a bytevector, or #f."
+  (match (assoc-ref (distribution-digests distribution) "sha256")
+    (#f #f)
+    (str (base16-string->bytevector str))))
+
 (define (pypi-fetch name)
   "Return a <pypi-project> record for package NAME, or #f on failure."
   (and=> (json-fetch (string-append (%pypi-base-url) name "/json"))
@@ -198,7 +208,9 @@ (define (maybe-inputs package-inputs input-type)
     (()
      '())
     ((package-inputs ...)
-     `((,input-type (list ,@package-inputs))))))
+     `((,input-type (list ,@(map (compose string->symbol
+                                          upstream-input-downstream-name)
+                                 package-inputs)))))))
 
 (define %requirement-name-regexp
   ;; Regexp to match the requirement name in a requirement specification.
@@ -409,23 +421,36 @@ (define (guess-requirements source-url wheel-url archive)
 
 (define (compute-inputs source-url wheel-url archive)
   "Given the SOURCE-URL and WHEEL-URL of an already downloaded ARCHIVE, return
-a pair of lists, each consisting of a list of name/variable pairs, for the
-propagated inputs and the native inputs, respectively.  Also
-return the unaltered list of upstream dependency names."
-
-  (define (strip-argparse deps)
-    (remove (cut string=? "argparse" <>) deps))
-
-  (define (requirement->package-name/sort deps)
-    (map string->symbol
-         (sort (map python->package-name deps) string-ci<?)))
-
-  (define process-requirements
-    (compose requirement->package-name/sort strip-argparse))
-
+the corresponding list of <upstream-input> records."
+  (define (requirements->upstream-inputs deps type)
+    (filter-map (match-lambda
+                  ("argparse" #f)
+                  (name (upstream-input
+                         (name name)
+                         (downstream-name (python->package-name name))
+                         (type type))))
+                (sort deps string-ci<?)))
+
+  ;; TODO: Record version number ranges in <upstream-input>.
   (let ((dependencies (guess-requirements source-url wheel-url archive)))
-    (values (map process-requirements dependencies)
-            (concatenate dependencies))))
+    (match dependencies
+      ((propagated native)
+       (append (requirements->upstream-inputs propagated 'propagated)
+               (requirements->upstream-inputs native 'native))))))
+
+(define* (pypi-package-inputs pypi-package #:optional version)
+  "Return the list of <upstream-input> for PYPI-PACKAGE.  This procedure
+downloads the source and possibly the wheel of PYPI-PACKAGE."
+  (let* ((info       (pypi-project-info pypi-package))
+         (version    (or version (project-info-version info)))
+         (dist       (source-release pypi-package version))
+         (source-url (distribution-url dist))
+         (wheel-url  (and=> (wheel-release pypi-package version)
+                            distribution-url)))
+    (call-with-temporary-output-file
+     (lambda (archive port)
+       (and (url-fetch source-url archive)
+            (compute-inputs source-url wheel-url archive))))))
 
 (define (find-project-url name pypi-url)
   "Try different project name substitution until the result is found in
@@ -445,52 +470,85 @@ (define (find-project-url name pypi-url)
 a substring of the PyPI URI that identifies the package.")  pypi-url name))
 name)))
 
-(define (make-pypi-sexp name version source-url wheel-url home-page synopsis
-                        description license)
-  "Return the `package' s-expression for a python package with the given NAME,
-VERSION, SOURCE-URL, HOME-PAGE, SYNOPSIS, DESCRIPTION, and LICENSE."
+(define* (pypi-package->upstream-source pypi-package #:optional version)
+  "Return the upstream source for the given VERSION of PYPI-PACKAGE, a
+<pypi-project> record.  If VERSION is omitted or #f, use the latest version."
+  (let* ((info       (pypi-project-info pypi-package))
+         (version    (or version (project-info-version info)))
+         (dist       (source-release pypi-package version))
+         (source-url (distribution-url dist))
+         (wheel-url  (and=> (wheel-release pypi-package version)
+                            distribution-url)))
+    (let ((extra-inputs (if (string-suffix? ".zip" source-url)
+                            (list (upstream-input
+                                   (name "zip")
+                                   (downstream-name "zip")
+                                   (type 'native)))
+                            '())))
+      (upstream-source
+       (urls (list source-url))
+       (signature-urls
+        (if (distribution-has-signature? dist)
+            (list (string-append source-url ".asc"))
+            #f))
+       (inputs (append (pypi-package-inputs pypi-package)
+                       extra-inputs))
+       (package (project-info-name info))
+       (version version)))))
+
+(define* (make-pypi-sexp pypi-package
+                         #:optional (version (latest-version pypi-package)))
+  "Return the `package' s-expression the given VERSION of PYPI-PACKAGE, a
+<pypi-project> record."
   (define (maybe-upstream-name name)
     (if (string-match ".*\\-[0-9]+" name)
         `((properties ,`'(("upstream-name" . ,name))))
         '()))
-  
-  (call-with-temporary-output-file
-   (lambda (temp port)
-     (and (url-fetch source-url temp)
-          (receive (guix-dependencies upstream-dependencies)
-              (compute-inputs source-url wheel-url temp)
-            (match guix-dependencies
-              ((required-inputs native-inputs)
-               (when (string-suffix? ".zip" source-url)
-                 (set! native-inputs (cons 'unzip native-inputs)))
-               (values
-                `(package
-                   (name ,(python->package-name name))
-                   (version ,version)
-                   (source
-                    (origin
-                      (method url-fetch)
-                      (uri (pypi-uri
-                             ,(find-project-url name source-url)
-                             version
-                             ;; Some packages have been released as `.zip`
-                             ;; instead of the more common `.tar.gz`. For
-                             ;; example, see "path-and-address".
-                             ,@(if (string-suffix? ".zip" source-url)
-                                   '(".zip")
-                                   '())))
-                      (sha256
-                       (base32
-                        ,(guix-hash-url temp)))))
-                   ,@(maybe-upstream-name name)
-                   (build-system pyproject-build-system)
-                   ,@(maybe-inputs required-inputs 'propagated-inputs)
-                   ,@(maybe-inputs native-inputs 'native-inputs)
-                   (home-page ,home-page)
-                   (synopsis ,synopsis)
-                   (description ,(beautify-description description))
-                   (license ,(license->symbol license)))
-                upstream-dependencies))))))))
+
+  (let* ((info (pypi-project-info pypi-package))
+         (name (project-info-name info))
+         (source-url (and=> (source-release pypi-package version)
+                            distribution-url))
+         (sha256 (and=> (source-release pypi-package version)
+                        distribution-sha256))
+         (source (pypi-package->upstream-source pypi-package version)))
+    (values
+     `(package
+        (name ,(python->package-name name))
+        (version ,version)
+        (source
+         (origin
+           (method url-fetch)
+           (uri (pypi-uri
+                 ,(find-project-url name source-url)
+                 version
+                 ;; Some packages have been released as `.zip`
+                 ;; instead of the more common `.tar.gz`. For
+                 ;; example, see "path-and-address".
+                 ,@(if (string-suffix? ".zip" source-url)
+                       '(".zip")
+                       '())))
+           (sha256 (base32
+                    ,(and=> (or sha256
+                                (let* ((port (http-fetch source-url))
+                                       (hash (port-sha256 port)))
+                                  (close-port port)
+                                  hash))
+                            bytevector->nix-base32-string)))))
+        ,@(maybe-upstream-name name)
+        (build-system pyproject-build-system)
+        ,@(maybe-inputs (upstream-source-propagated-inputs source)
+                        'propagated-inputs)
+        ,@(maybe-inputs (upstream-source-native-inputs source)
+                        'native-inputs)
+        (home-page ,(project-info-home-page info))
+        (synopsis ,(project-info-summary info))
+        (description ,(beautify-description
+                       (project-info-summary info)))
+        (license ,(license->symbol
+                   (string->license
+                    (project-info-license info)))))
+     (map upstream-input-name (upstream-source-inputs source)))))
 
 (define pypi->guix-package
   (memoize
@@ -520,16 +578,7 @@ (define pypi->guix-package
 source.  To build it from source, refer to the upstream repository at
 @uref{~a}.")
                                               url))))))))))))
-             (make-pypi-sexp (project-info-name info) version
-                             (and=> (source-release project version)
-                                    distribution-url)
-                             (and=> (wheel-release project version)
-                                    distribution-url)
-                             (project-info-home-page info)
-                             (project-info-summary info)
-                             (project-info-summary info)
-                             (string->license
-                              (project-info-license info))))
+             (make-pypi-sexp project version))
            (values #f '()))))))
 
 (define* (pypi-recursive-import package-name #:optional version)
@@ -566,21 +615,7 @@ (define* (import-release package #:key (version #f))
          (pypi-package (pypi-fetch pypi-name)))
     (and pypi-package
          (guard (c ((missing-source-error? c) #f))
-           (let* ((info    (pypi-project-info pypi-package))
-                  (version (or version (project-info-version info)))
-                  (dist    (source-release pypi-package version))
-                  (url     (distribution-url dist)))
-             (upstream-source
-              (urls (list url))
-              (signature-urls
-               (if (distribution-has-signature? dist)
-                   (list (string-append url ".asc"))
-                   #f))
-              (input-changes
-               (changed-inputs package
-                               (pypi->guix-package pypi-name #:version version)))
-              (package (package-name package))
-              (version version)))))))
+           (pypi-package->upstream-source pypi-package version)))))
 
 (define %pypi-updater
   (upstream-updater
diff --git a/guix/import/stackage.scm b/guix/import/stackage.scm
index f98b86c334..f8b2726591 100644
--- a/guix/import/stackage.scm
+++ b/guix/import/stackage.scm
@@ -29,6 +29,7 @@ (define-module (guix import stackage)
   #:use-module (srfi srfi-35)
   #:use-module (guix import json)
   #:use-module (guix import hackage)
+  #:autoload   (guix import cabal) (eval-cabal)
   #:use-module (guix import utils)
   #:use-module (guix memoization)
   #:use-module (guix packages)
@@ -157,15 +158,13 @@ (define latest-lts-release
            (warning (G_ "failed to parse ~a~%")
                     (hackage-cabal-url hackage-name))
            #f)
-          (_ (let ((url (hackage-source-url hackage-name version)))
+          (_ (let ((url (hackage-source-url hackage-name version))
+                   (cabal (eval-cabal (hackage-fetch hackage-name) '())))
                (upstream-source
                 (package (package-name pkg))
                 (version version)
                 (urls (list url))
-                (input-changes
-                 (changed-inputs
-                  pkg
-                  (stackage->guix-package hackage-name #:packages (packages))))))))))))
+                (inputs (cabal-package-inputs cabal))))))))))
 
 (define (stackage-lts-package? package)
   "Return whether PACKAGE is available on the default Stackage LTS release."
diff --git a/guix/scripts/refresh.scm b/guix/scripts/refresh.scm
index bfa6269aa3..d838a4aca2 100644
--- a/guix/scripts/refresh.scm
+++ b/guix/scripts/refresh.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013-2022 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013-2023 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org>
 ;;; Copyright © 2014 Eric Bavier <bavier@member.fsf.org>
 ;;; Copyright © 2015 Alex Kost <alezost@gmail.com>
@@ -404,7 +404,7 @@ (define* (update-package store package version updaters
                      (('remove 'propagated)
                       (info loc (G_ "~a: consider removing this propagated input: ~a~%")
                             name change-name))))
-                 (upstream-source-input-changes source))
+                 (changed-inputs package source))
                 (let ((hash (file-hash* output)))
                   (update-package-source package source hash)))
               (warning (G_ "~a: version ~a could not be \
diff --git a/guix/upstream.scm b/guix/upstream.scm
index aac501c466..52f9333878 100644
--- a/guix/upstream.scm
+++ b/guix/upstream.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2010-2022 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2010-2023 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2015 Alex Kost <alezost@gmail.com>
 ;;; Copyright © 2019, 2022 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2021 Sarah Morgensen <iskarian@mgsn.dev>
@@ -55,7 +55,20 @@ (define-module (guix upstream)
             upstream-source-urls
             upstream-source-signature-urls
             upstream-source-archive-types
-            upstream-source-input-changes
+            upstream-source-inputs
+
+            upstream-input-type-predicate
+            upstream-source-regular-inputs
+            upstream-source-native-inputs
+            upstream-source-propagated-inputs
+
+            upstream-input
+            upstream-input?
+            upstream-input-name
+            upstream-input-downstream-name
+            upstream-input-type
+            upstream-input-min-version
+            upstream-input-max-version
 
             url-predicate
             url-prefix-predicate
@@ -102,8 +115,40 @@ (define-record-type* <upstream-source>
   (urls           upstream-source-urls)           ;list of strings|git-reference
   (signature-urls upstream-source-signature-urls  ;#f | list of strings
                   (default #f))
-  (input-changes  upstream-source-input-changes
-                  (default '()) (thunked)))
+  (inputs         upstream-source-inputs        ;#f | list of <upstream-input>
+                  (delayed) (default #f))) ;delayed because optional and costly
+
+;; Representation of a dependency as expressed by upstream.
+(define-record-type* <upstream-input>
+  upstream-input make-upstream-input
+  upstream-input?
+  (name         upstream-input-name)               ;upstream package name
+  (downstream-name upstream-input-downstream-name) ;Guix package name
+  (type         upstream-input-type          ;'regular | 'native | 'propagated
+                (default 'regular))
+  (min-version  upstream-input-min-version
+                (default 'any))
+  (max-version  upstream-input-max-version
+                (default 'any)))
+
+(define (upstream-input-type-predicate type)
+  "Return a predicate that returns true when passed an <upstream-input> record
+of the given TYPE (a symbol such as 'propagated)."
+  (lambda (source)
+    (eq? type (upstream-input-type source))))
+
+(define (input-type-filter type)
+  "Return a procedure that, given an <upstream-source>, returns the subset of
+its inputs that have the given TYPE (a symbol such as 'native)."
+  (lambda (source)
+    "Return the subset of inputs of SOURCE that have the given TYPE."
+    (filter (lambda (input)
+              (eq? type (upstream-input-type input)))
+            (upstream-source-inputs source))))
+
+(define upstream-source-regular-inputs (input-type-filter 'regular))
+(define upstream-source-native-inputs (input-type-filter 'native))
+(define upstream-source-propagated-inputs (input-type-filter 'propagated))
 
 ;; Representation of an upstream input change.
 (define-record-type* <upstream-input-change>
@@ -113,67 +158,55 @@ (define-record-type* <upstream-input-change>
   (type    upstream-input-change-type)    ;symbol: regular | native | propagated
   (action  upstream-input-change-action)) ;symbol: add | remove
 
-(define (changed-inputs package package-sexp)
-  "Return a list of input changes for PACKAGE based on the newly imported
-S-expression PACKAGE-SEXP."
-  (match package-sexp
-    ((and expr ('package fields ...))
-     (let* ((input->name (match-lambda ((name pkg . out) name)))
-            (new-regular
-             (match expr
-               ((path *** ('inputs
-                           ('quasiquote ((label ('unquote sym)) ...)))) label)
-               ((path *** ('inputs
-                           ('list sym ...))) (map symbol->string sym))
-               (_ '())))
-            (new-native
-             (match expr
-               ((path *** ('native-inputs
-                           ('quasiquote ((label ('unquote sym)) ...)))) label)
-               ((path *** ('native-inputs
-                           ('list sym ...))) (map symbol->string sym))
-               (_ '())))
-            (new-propagated
-             (match expr
-               ((path *** ('propagated-inputs
-                           ('quasiquote ((label ('unquote sym)) ...)))) label)
-               ((path *** ('propagated-inputs
-                           ('list sym ...))) (map symbol->string sym))
-               (_ '())))
-            (current-regular
-             (map input->name (package-inputs package)))
-            (current-native
-             (map input->name (package-native-inputs package)))
-            (current-propagated
-             (map input->name (package-propagated-inputs package))))
-       (append-map
-        (match-lambda
-          ((action type names)
-           (map (lambda (name)
-                  (upstream-input-change
-                   (name name)
-                   (type type)
-                   (action action)))
-                names)))
-        `((add regular
-           ,(lset-difference equal?
-                             new-regular current-regular))
-          (remove regular
-           ,(lset-difference equal?
-                             current-regular new-regular))
-          (add native
-           ,(lset-difference equal?
-                             new-native current-native))
-          (remove native
-           ,(lset-difference equal?
-                             current-native new-native))
-          (add propagated
-           ,(lset-difference equal?
-                             new-propagated current-propagated))
-          (remove propagated
-           ,(lset-difference equal?
-                             current-propagated new-propagated))))))
-    (_ '())))
+(define (changed-inputs package source)
+  "Return a list of input changes for PACKAGE compared to the 'inputs' field
+of SOURCE, an <upstream-source> record."
+  (define input->name
+    (match-lambda
+      ((label (? package? pkg) . out) (package-name pkg))
+      (_ #f)))
+
+  (if (upstream-source-inputs source)
+      (let* ((new-regular (map upstream-input-downstream-name
+                               (upstream-source-regular-inputs source)))
+             (new-native (map upstream-input-downstream-name
+                              (upstream-source-native-inputs source)))
+             (new-propagated (map upstream-input-downstream-name
+                                  (upstream-source-propagated-inputs source)))
+             (current-regular
+              (filter-map input->name (package-inputs package)))
+             (current-native
+              (filter-map input->name (package-native-inputs package)))
+             (current-propagated
+              (filter-map input->name (package-propagated-inputs package))))
+        (append-map
+         (match-lambda
+           ((action type names)
+            (map (lambda (name)
+                   (upstream-input-change
+                    (name name)
+                    (type type)
+                    (action action)))
+                 names)))
+         `((add regular
+                ,(lset-difference equal?
+                                  new-regular current-regular))
+           (remove regular
+                   ,(lset-difference equal?
+                                     current-regular new-regular))
+           (add native
+                ,(lset-difference equal?
+                                  new-native current-native))
+           (remove native
+                   ,(lset-difference equal?
+                                     current-native new-native))
+           (add propagated
+                ,(lset-difference equal?
+                                  new-propagated current-propagated))
+           (remove propagated
+                   ,(lset-difference equal?
+                                     current-propagated new-propagated)))))
+      '()))
 
 (define* (url-predicate matching-url?)
   "Return a predicate that returns true when passed a package whose source is
diff --git a/tests/pypi.scm b/tests/pypi.scm
index 497744511f..f3b2771f4b 100644
--- a/tests/pypi.scm
+++ b/tests/pypi.scm
@@ -25,9 +25,12 @@ (define-module (test-pypi)
   #:use-module (guix base32)
   #:use-module (guix memoization)
   #:use-module (guix utils)
+  #:use-module ((guix base16) #:select (base16-string->bytevector))
+  #:use-module (guix upstream)
   #:use-module (gcrypt hash)
   #:use-module (guix tests)
   #:use-module (guix tests http)
+  #:use-module ((guix download) #:select (url-fetch))
   #:use-module (guix build-system python)
   #:use-module ((guix build utils)
                 #:select (delete-file-recursively
@@ -43,6 +46,12 @@ (define-module (test-pypi)
   #:use-module (ice-9 match)
   #:use-module (ice-9 optargs))
 
+(define default-sha256
+  "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
+(define default-sha256/base32
+  (bytevector->nix-base32-string
+   (base16-string->bytevector default-sha256)))
+
 (define* (foo-json #:key (name "foo") (name-in-url #f))
   "Create a JSON description of an example pypi package, named @var{name},
 optionally using a different @var{name in its URL}."
@@ -65,7 +74,8 @@ (define* (foo-json #:key (name "foo") (name-in-url #f))
               ((url . ,(format #f "~a/~a-1.0.0.tar.gz"
                                (%local-url #:path "")
                                (or name-in-url name)))
-               (packagetype . "sdist"))
+               (packagetype . "sdist")
+               (digests . (("sha256" . ,default-sha256))))
               ((url . ,(format #f "~a/~a-1.0.0-py2.py3-none-any.whl"
                                (%local-url #:path "")
                                (or name-in-url name)))
@@ -308,9 +318,7 @@ (define-syntax-rule (with-pypi responses body ...)
            ('synopsis "summary")
            ('description "summary")
            ('license 'license:lgpl2.0))
-         (and (string=? (bytevector->nix-base32-string
-                         (file-sha256 tarball))
-                        hash)
+         (and (string=? default-sha256/base32 hash)
               (equal? (pypi->guix-package "foo" #:version "1.0.0")
                       (pypi->guix-package "foo"))
               (guard (c ((error? c) #t))
@@ -352,8 +360,7 @@ (define-syntax-rule (with-pypi responses body ...)
            ('synopsis "summary")
            ('description "summary")
            ('license 'license:lgpl2.0))
-         (string=? (bytevector->nix-base32-string (file-sha256 tarball))
-                   hash))
+         (string=? default-sha256/base32 hash))
         (x
          (pk 'fail x #f))))))
 
@@ -382,8 +389,7 @@ (define-syntax-rule (with-pypi responses body ...)
            ('synopsis "summary")
            ('description "summary")
            ('license 'license:lgpl2.0))
-         (string=? (bytevector->nix-base32-string (file-sha256 tarball))
-                   hash))
+         (string=? default-sha256/base32 hash))
         (x
          (pk 'fail x #f))))))
 
@@ -414,11 +420,47 @@ (define-syntax-rule (with-pypi responses body ...)
            ('synopsis "summary")
            ('description "summary")
            ('license 'license:lgpl2.0))
-         (string=? (bytevector->nix-base32-string (file-sha256 tarball))
-                   hash))
+         (string=? default-sha256/base32 hash))
         (x
          (pk 'fail x #f))))))
 
+(test-equal "package-latest-release"
+  (list '("foo-1.0.0.tar.gz")
+        '("foo-1.0.0.tar.gz.asc")
+        (list (upstream-input
+               (name "bar")
+               (downstream-name "python-bar")
+               (type 'propagated))
+              (upstream-input
+               (name "foo")
+               (downstream-name "python-foo")
+               (type 'propagated))
+              (upstream-input
+               (name "pytest")
+               (downstream-name "python-pytest")
+               (type 'native))))
+  (let ((tarball (pypi-tarball
+                  "foo-1.0.0"
+                  `(("src/bizarre.egg-info/requires.txt"
+                     ,test-requires.txt)))))
+    (with-pypi `(("/foo-1.0.0.tar.gz" 200 ,(file-dump tarball))
+                 ("/foo-1.0.0-py2.py3-none-any.whl" 404 "")
+                 ("/foo/json" 200 ,(lambda (port)
+                                     (display (foo-json) port))))
+      (define source
+        (package-latest-release
+         (dummy-package "python-foo"
+                        (version "0.1.2")
+                        (source (dummy-origin
+                                 (method url-fetch)
+                                 (uri (pypi-uri "foo" version))))
+                        (build-system python-build-system))
+         (list %pypi-updater)))
+
+      (list (map basename (upstream-source-urls source))
+            (map basename (upstream-source-signature-urls source))
+            (upstream-source-inputs source)))))
+
 (test-end "pypi")
 (delete-file-recursively sample-directory)
 
diff --git a/tests/upstream.scm b/tests/upstream.scm
index 9aacb77229..0792ebd5d0 100644
--- a/tests/upstream.scm
+++ b/tests/upstream.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2016 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2016, 2023 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2022 Ricardo Wurmus <rekado@elephly.net>
 ;;;
 ;;; This file is part of GNU Guix.
@@ -78,69 +78,29 @@ (define test-package
     (description "test")
     (license license:gpl3+)))
 
-(define test-package-sexp
-  '(package
-    (name "test")
-    (version "2.10")
-    (source (origin
-              (method url-fetch)
-              (uri (string-append "mirror://gnu/hello/hello-" version
-                                  ".tar.gz"))
-              (sha256
-               (base32
-                "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
-    (build-system gnu-build-system)
-    (inputs
-     `(("hello" ,hello)))
-    (native-inputs
-     `(("sed" ,sed)
-       ("tar" ,tar)))
-    (propagated-inputs
-     `(("grep" ,grep)))
-    (home-page "http://localhost")
-    (synopsis "test")
-    (description "test")
-    (license license:gpl3+)))
-
 (test-equal "changed-inputs returns no changes"
   '()
-  (changed-inputs test-package test-package-sexp))
-
-(test-assert "changed-inputs returns changes to labelled input list"
-  (let ((changes (changed-inputs
-                  (package
-                    (inherit test-package)
-                    (inputs `(("hello" ,hello)
-                              ("sed" ,sed))))
-                  test-package-sexp)))
-    (match changes
-      ;; Exactly one change
-      (((? upstream-input-change? item))
-       (and (equal? (upstream-input-change-type item)
-                    'regular)
-            (equal? (upstream-input-change-action item)
-                    'remove)
-            (string=? (upstream-input-change-name item)
-                      "sed")))
-      (else (pk else #false)))))
-
-(test-assert "changed-inputs returns changes to all labelled input lists"
-  (let ((changes (changed-inputs
-                  (package
-                    (inherit test-package)
-                    (inputs '())
-                    (native-inputs '())
-                    (propagated-inputs '()))
-                  test-package-sexp)))
-    (match changes
-      (((? upstream-input-change? items) ...)
-       (and (equal? (map upstream-input-change-type items)
-                    '(regular native native propagated))
-            (equal? (map upstream-input-change-action items)
-                    '(add add add add))
-            (equal? (map upstream-input-change-name items)
-                    '("hello" "sed" "tar" "grep"))))
-      (else (pk else #false)))))
+  (changed-inputs test-package
+                  (upstream-source
+                   (package "test")
+                   (version "1")
+                   (urls '())
+                   (inputs
+                    (let ((->input
+                           (lambda (type)
+                             (match-lambda
+                               ((label _)
+                                (upstream-input
+                                 (name label)
+                                 (downstream-name label)
+                                 (type type)))))))
+                      (append (map (->input 'regular)
+                                   (package-inputs test-package))
+                              (map (->input 'native)
+                                   (package-native-inputs test-package))
+                              (map (->input 'propagated)
+                                   (package-propagated-inputs
+                                    test-package))))))))
 
 (define test-new-package
   (package
@@ -152,35 +112,20 @@ (define test-new-package
     (propagated-inputs
      (list grep))))
 
-(define test-new-package-sexp
-  '(package
-    (name "test")
-    (version "2.10")
-    (source (origin
-              (method url-fetch)
-              (uri (string-append "mirror://gnu/hello/hello-" version
-                                  ".tar.gz"))
-              (sha256
-               (base32
-                "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
-    (build-system gnu-build-system)
-    (inputs
-     (list hello))
-    (native-inputs
-     (list sed tar))
-    (propagated-inputs
-     (list grep))
-    (home-page "http://localhost")
-    (synopsis "test")
-    (description "test")
-    (license license:gpl3+)))
-
 (test-assert "changed-inputs returns changes to plain input list"
   (let ((changes (changed-inputs
                   (package
                     (inherit test-new-package)
-                    (inputs (list hello sed)))
-                  test-new-package-sexp)))
+                    (inputs (list hello sed))
+                    (native-inputs '())
+                    (propagated-inputs '()))
+                  (upstream-source
+                   (package "test")
+                   (version "1")
+                   (urls '())
+                   (inputs (list (upstream-input
+                                  (name "hello")
+                                  (downstream-name name))))))))
     (match changes
       ;; Exactly one change
       (((? upstream-input-change? item))
@@ -199,7 +144,26 @@ (define test-new-package-sexp
                     (inputs '())
                     (native-inputs '())
                     (propagated-inputs '()))
-                  test-new-package-sexp)))
+                  (upstream-source
+                   (package "test")
+                   (version "1")
+                   (urls '())
+                   (inputs (list (upstream-input
+                                  (name "hello")
+                                  (downstream-name name)
+                                  (type 'regular))
+                                 (upstream-input
+                                  (name "sed")
+                                  (downstream-name name)
+                                  (type 'native))
+                                 (upstream-input
+                                  (name "tar")
+                                  (downstream-name name)
+                                  (type 'native))
+                                 (upstream-input
+                                  (name "grep")
+                                  (downstream-name name)
+                                  (type 'propagated))))))))
     (match changes
       (((? upstream-input-change? items) ...)
        (and (equal? (map upstream-input-change-type items)
