Initial import

README.md

@@ -1,3 +1,28 @@
 # uni-channel
 
-Encapsulating async-channel, port-channel and place-channel. 
+`uni-channel` provides a uniform facade over `async-channel`, `place-channel` and `port-channel`.
+
+The package does not vendor `port-channel`; install `port-channel` from the Racket package index first.
+
+```sh
+raco pkg install --auto port-channel
+raco pkg install --auto ./uni-channel
+raco test -x -p uni-channel
+raco setup --pkgs uni-channel
+```
+
+Main API:
+
+```racket
+make-uni-channel
+make-uni-async-channel
+make-uni-async-channel-pair
+make-uni-place-channel
+make-uni-place-channel-pair
+make-uni-port-channel
+uni-channel-put
+uni-channel-get
+uni-channel-send
+uni-channel-recv
+uni-channel-close
+```

info.rkt

@@ -0,0 +1,17 @@
+#lang info
+
+(define collection "uni-channel")
+(define pkg-authors '(hnmdijkema))
+(define version "0.1")
+(define license '(Apache-2.0 OR MIT))
+(define pkg-desc "Uniform channel facade for place-channel, async-channel and port-channel.")
+
+(define deps '("base" "port-channel"))
+(define build-deps '("racket-doc" "scribble-lib" "rackunit-lib"))
+
+;; Keep package installation from compiling the tests as runtime modules.
+;; `rackunit-lib` is a build/test dependency, not a library dependency.
+(define compile-omit-paths '("test"))
+
+(define scribblings
+  '(("scribblings/uni-channel.scrbl" () (library))))

main.rkt

@@ -0,0 +1,335 @@
+#lang racket/base
+
+(require racket/async-channel
+         racket/place
+         port-channel)
+
+(provide uni-channel?
+         uni-channel-kind
+         uni-channel-direction
+         uni-channel-name
+         uni-channel-impl
+
+         make-uni-channel
+         make-uni-async-channel
+         make-uni-async-channel-pair
+         make-uni-place-channel
+         make-uni-place-channel-pair
+         make-uni-port-channel
+
+         uni-channel-put
+         uni-channel-get
+         uni-channel-send
+         uni-channel-recv
+         uni-channel-try-get
+         uni-channel-get-evt
+         uni-channel-put-evt
+         uni-channel-close
+         uni-channel-closed?
+
+         uni-channel-error-get
+         uni-channel-error-try-get
+         uni-channel-error-evt)
+
+(struct uni-channel
+  (kind impl direction name get-proc put-proc try-get-proc get-evt-proc put-evt-proc
+        close-proc closed-box error-get-proc error-try-get-proc error-evt-proc)
+  #:property prop:evt
+  (lambda (ch)
+    (cond
+      [(and (can-get? ch) (uni-channel-get-proc ch))
+       ((uni-channel-get-evt-proc ch) ch)]
+      [else never-evt])))
+
+(define (check-direction who v)
+  (case v
+    [(input output bidirectional) v]
+    [else (raise-argument-error who "(or/c 'input 'output 'bidirectional)" v)]))
+
+(define (check-kind who v)
+  (case v
+    [(async place port custom) v]
+    [else (raise-argument-error who "(or/c 'async 'place 'port 'custom)" v)]))
+
+(define (can-get? ch)
+  (not (eq? (uni-channel-direction ch) 'output)))
+
+(define (can-put? ch)
+  (not (eq? (uni-channel-direction ch) 'input)))
+
+(define (raise-no-get who ch)
+  (raise-arguments-error who "uni-channel does not support receiving"
+                         "name" (uni-channel-name ch)
+                         "direction" (uni-channel-direction ch)))
+
+(define (raise-no-put who ch)
+  (raise-arguments-error who "uni-channel does not support sending"
+                         "name" (uni-channel-name ch)
+                         "direction" (uni-channel-direction ch)))
+
+(define (raise-closed who ch)
+  (raise-arguments-error who "uni-channel is closed"
+                         "name" (uni-channel-name ch)
+                         "kind" (uni-channel-kind ch)))
+
+(define (closed-box) (box #f))
+
+(define (mark-closed! ch)
+  (set-box! (uni-channel-closed-box ch) #t))
+
+(define (default-close ch)
+  (mark-closed! ch)
+  (void))
+
+(define (no-error-get ch)
+  (raise-arguments-error 'uni-channel-error-get "uni-channel has no error channel"
+                         "name" (uni-channel-name ch)
+                         "kind" (uni-channel-kind ch)))
+
+(define (no-error-try-get ch) #f)
+(define (no-error-evt ch) never-evt)
+
+(define (make-oc #:kind kind
+                 #:backend backend
+                 #:direction direction
+                 #:name name
+                 #:get get-proc
+                 #:put put-proc
+                 #:try-get try-get-proc
+                 #:get-evt get-evt-proc
+                 #:put-evt put-evt-proc
+                 #:close close-proc
+                 #:error-get error-get-proc
+                 #:error-try-get error-try-get-proc
+                 #:error-evt error-evt-proc)
+  (uni-channel kind backend direction name get-proc put-proc try-get-proc get-evt-proc put-evt-proc
+                  close-proc (closed-box) error-get-proc error-try-get-proc error-evt-proc))
+
+(define (make-uni-channel backend
+                             #:kind [kind 'auto]
+                             #:direction [direction 'auto]
+                             #:name [name #f])
+  (define detected-kind
+    (case kind
+      [(auto)
+       (cond
+         [(async-channel? backend) 'async]
+         [(place-channel? backend) 'place]
+         [(port-channel? backend) 'port]
+         [else (raise-argument-error 'make-uni-channel
+                                     "(or/c async-channel? place-channel? port-channel?)"
+                                     backend)])]
+      [else (check-kind 'make-uni-channel kind)]))
+  (case detected-kind
+    [(async)
+     (unless (async-channel? backend)
+       (raise-argument-error 'make-uni-channel "async-channel?" backend))
+     (make-uni-async-channel backend #:direction direction #:name (or name 'async-channel))]
+    [(place)
+     (unless (place-channel? backend)
+       (raise-argument-error 'make-uni-channel "place-channel?" backend))
+     (make-uni-place-channel backend #:direction direction #:name (or name 'place-channel))]
+    [(port)
+     (unless (port-channel? backend)
+       (raise-argument-error 'make-uni-channel "port-channel?" backend))
+     (define pc-dir (port-channel-direction backend))
+     (define dir (if (eq? direction 'auto) pc-dir (check-direction 'make-uni-channel direction)))
+     (unless (eq? pc-dir dir)
+       (raise-arguments-error 'make-uni-channel "direction does not match port-channel direction"
+                              "requested direction" dir
+                              "port-channel direction" pc-dir))
+     (make-port-oc (and (eq? pc-dir 'input) backend)
+                   (and (eq? pc-dir 'output) backend)
+                   #:direction pc-dir
+                   #:name (or name 'port-channel))]
+    [else
+     (raise-argument-error 'make-uni-channel "(or/c 'auto 'async 'place 'port)" kind)]))
+
+(define (make-uni-async-channel [ch (make-async-channel)]
+                                   #:direction [direction 'bidirectional]
+                                   #:name [name 'async-channel])
+  (define dir (if (eq? direction 'auto) 'bidirectional (check-direction 'make-uni-async-channel direction)))
+  (define backend ch)
+  (make-oc #:kind 'async
+           #:backend backend
+           #:direction dir
+           #:name name
+           #:get (lambda (_ch) (async-channel-get backend))
+           #:put (lambda (_ch v) (async-channel-put backend v))
+           #:try-get (lambda (_ch) (async-channel-try-get backend))
+           #:get-evt (lambda (_ch) backend)
+           #:put-evt (lambda (_ch v) (async-channel-put-evt backend v))
+           #:close default-close
+           #:error-get no-error-get
+           #:error-try-get no-error-try-get
+           #:error-evt no-error-evt))
+
+(define (make-uni-async-channel-pair #:name-a [name-a 'async-channel-a]
+                                        #:name-b [name-b 'async-channel-b])
+  (define a-in (make-async-channel))
+  (define b-in (make-async-channel))
+  (define (endpoint name incoming outgoing)
+    (make-oc #:kind 'async
+             #:backend (vector 'async-channel-pair incoming outgoing)
+             #:direction 'bidirectional
+             #:name name
+             #:get (lambda (_ch) (async-channel-get incoming))
+             #:put (lambda (_ch v) (async-channel-put outgoing v))
+             #:try-get (lambda (_ch) (async-channel-try-get incoming))
+             #:get-evt (lambda (_ch) incoming)
+             #:put-evt (lambda (_ch v) (async-channel-put-evt outgoing v))
+             #:close default-close
+             #:error-get no-error-get
+             #:error-try-get no-error-try-get
+             #:error-evt no-error-evt))
+  (values (endpoint name-a a-in b-in) (endpoint name-b b-in a-in)))
+
+(define (make-uni-place-channel ch
+                                   #:direction [direction 'bidirectional]
+                                   #:name [name 'place-channel])
+  (define dir (if (eq? direction 'auto) 'bidirectional (check-direction 'make-uni-place-channel direction)))
+  (define backend ch)
+  (make-oc #:kind 'place
+           #:backend backend
+           #:direction dir
+           #:name name
+           #:get (lambda (_ch) (place-channel-get backend))
+           #:put (lambda (_ch v) (place-channel-put backend v))
+           #:try-get (lambda (_ch) (sync/timeout 0 backend))
+           #:get-evt (lambda (_ch) backend)
+           #:put-evt (lambda (_ch v) (handle-evt always-evt (lambda (_) (place-channel-put backend v))))
+           #:close default-close
+           #:error-get no-error-get
+           #:error-try-get no-error-try-get
+           #:error-evt no-error-evt))
+
+(define (make-uni-place-channel-pair #:name-a [name-a 'place-channel-a]
+                                        #:name-b [name-b 'place-channel-b])
+  (define-values (a b) (place-channel))
+  (values (make-uni-place-channel a #:name name-a)
+          (make-uni-place-channel b #:name name-b)))
+
+(define (make-port-oc in-pc out-pc #:direction direction #:name name)
+  (define backend
+    (cond
+      [(and in-pc out-pc) (vector 'port-channel-pair in-pc out-pc)]
+      [in-pc in-pc]
+      [out-pc out-pc]
+      [else (error 'make-port-oc "internal error: no port-channel backend")]))
+  (define (get* _ch) (port-channel-get in-pc))
+  (define (put* _ch v) (port-channel-put out-pc v))
+  (define (try-get* _ch) (port-channel-try-get in-pc))
+  (define (get-evt* _ch) (port-channel-evt in-pc))
+  (define (put-evt* _ch v) (handle-evt always-evt (lambda (_) (port-channel-put out-pc v))))
+  (define (close* ch)
+    (mark-closed! ch)
+    (cond
+      [(and in-pc out-pc) (close-port-channel out-pc)]
+      [in-pc (close-port-channel in-pc)]
+      [out-pc (close-port-channel out-pc)])
+    (void))
+  (define (error-get* _ch)
+    (cond
+      [in-pc (port-channel-error-get in-pc)]
+      [out-pc (port-channel-error-get out-pc)]))
+  (define (error-try-get* _ch)
+    (or (and in-pc (port-channel-error-try-get in-pc))
+        (and out-pc (port-channel-error-try-get out-pc))))
+  (define (error-evt* _ch)
+    (cond
+      [(and in-pc out-pc) (choice-evt (port-channel-error-evt in-pc) (port-channel-error-evt out-pc))]
+      [in-pc (port-channel-error-evt in-pc)]
+      [out-pc (port-channel-error-evt out-pc)]))
+  (make-oc #:kind 'port
+           #:backend backend
+           #:direction direction
+           #:name name
+           #:get (and in-pc get*)
+           #:put (and out-pc put*)
+           #:try-get (and in-pc try-get*)
+           #:get-evt (and in-pc get-evt*)
+           #:put-evt (and out-pc put-evt*)
+           #:close close*
+           #:error-get error-get*
+           #:error-try-get error-try-get*
+           #:error-evt error-evt*))
+
+(define (make-uni-port-channel #:input [in #f]
+                                  #:output [out #f]
+                                  #:source [source 'port-channel]
+                                  #:close? [close? #t]
+                                  #:name [name 'port-channel])
+  (unless (or in out)
+    (raise-arguments-error 'make-uni-port-channel
+                           "expected at least one of #:input or #:output"))
+  (when (and in (not (input-port? in)))
+    (raise-argument-error 'make-uni-port-channel "input-port?" in))
+  (when (and out (not (output-port? out)))
+    (raise-argument-error 'make-uni-port-channel "output-port?" out))
+  (define in-pc (and in (make-port-channel in #:direction 'input #:source source #:close? close?)))
+  (define out-pc (and out (make-port-channel out #:direction 'output #:source source #:close? close?)))
+  (define direction
+    (cond
+      [(and in-pc out-pc) 'bidirectional]
+      [in-pc 'input]
+      [else 'output]))
+  (make-port-oc in-pc out-pc #:direction direction #:name name))
+
+(define (uni-channel-closed? ch)
+  (unbox (uni-channel-closed-box ch)))
+
+(define (uni-channel-put ch v)
+  (unless (uni-channel? ch) (raise-argument-error 'uni-channel-put "uni-channel?" ch))
+  (unless (can-put? ch) (raise-no-put 'uni-channel-put ch))
+  (when (uni-channel-closed? ch) (raise-closed 'uni-channel-put ch))
+  (define put-proc (uni-channel-put-proc ch))
+  (unless put-proc (raise-no-put 'uni-channel-put ch))
+  (put-proc ch v))
+
+(define (uni-channel-get ch)
+  (unless (uni-channel? ch) (raise-argument-error 'uni-channel-get "uni-channel?" ch))
+  (unless (can-get? ch) (raise-no-get 'uni-channel-get ch))
+  (define get-proc (uni-channel-get-proc ch))
+  (unless get-proc (raise-no-get 'uni-channel-get ch))
+  (get-proc ch))
+
+(define uni-channel-send uni-channel-put)
+(define uni-channel-recv uni-channel-get)
+
+(define (uni-channel-try-get ch)
+  (unless (uni-channel? ch) (raise-argument-error 'uni-channel-try-get "uni-channel?" ch))
+  (unless (can-get? ch) (raise-no-get 'uni-channel-try-get ch))
+  (define try-get-proc (uni-channel-try-get-proc ch))
+  (unless try-get-proc (raise-no-get 'uni-channel-try-get ch))
+  (try-get-proc ch))
+
+(define (uni-channel-get-evt ch)
+  (unless (uni-channel? ch) (raise-argument-error 'uni-channel-get-evt "uni-channel?" ch))
+  (unless (can-get? ch) (raise-no-get 'uni-channel-get-evt ch))
+  (define get-evt-proc (uni-channel-get-evt-proc ch))
+  (unless get-evt-proc (raise-no-get 'uni-channel-get-evt ch))
+  (get-evt-proc ch))
+
+(define (uni-channel-put-evt ch v)
+  (unless (uni-channel? ch) (raise-argument-error 'uni-channel-put-evt "uni-channel?" ch))
+  (unless (can-put? ch) (raise-no-put 'uni-channel-put-evt ch))
+  (when (uni-channel-closed? ch) (raise-closed 'uni-channel-put-evt ch))
+  (define put-evt-proc (uni-channel-put-evt-proc ch))
+  (unless put-evt-proc (raise-no-put 'uni-channel-put-evt ch))
+  (put-evt-proc ch v))
+
+(define (uni-channel-close ch)
+  (unless (uni-channel? ch) (raise-argument-error 'uni-channel-close "uni-channel?" ch))
+  ((uni-channel-close-proc ch) ch))
+
+(define (uni-channel-error-get ch)
+  (unless (uni-channel? ch) (raise-argument-error 'uni-channel-error-get "uni-channel?" ch))
+  ((uni-channel-error-get-proc ch) ch))
+
+(define (uni-channel-error-try-get ch)
+  (unless (uni-channel? ch) (raise-argument-error 'uni-channel-error-try-get "uni-channel?" ch))
+  ((uni-channel-error-try-get-proc ch) ch))
+
+(define (uni-channel-error-evt ch)
+  (unless (uni-channel? ch) (raise-argument-error 'uni-channel-error-evt "uni-channel?" ch))
+  ((uni-channel-error-evt-proc ch) ch))

scribblings/uni-channel.scrbl

@@ -0,0 +1,167 @@
+#lang scribble/manual
+
+@(require (for-label racket/base
+                     racket/contract/base
+                     racket/async-channel
+                     racket/place
+                     racket/serialize
+                     port-channel
+                     uni-channel))
+
+@title{uni-channel}
+@author[@author+email["Hans Dijkema" "hans@dijkewijk.nl"]]
+
+@defmodule[uni-channel]
+
+The @racketmodname[uni-channel] module provides a small uniform facade over
+three channel-like transports: @racketmodname[racket/async-channel]
+asynchronous channels, @racketmodname[racket/place] place channels, and
+@racketmodname[port-channel] port channels.
+
+The purpose is not to hide transport semantics completely. A place channel still
+uses place-channel message constraints and a port channel still serializes values
+with @racketmodname[racket/serialize]. The purpose is to make code that only
+needs send, receive, event synchronization and close operations independent from
+the concrete channel implementation.
+
+@section{Model}
+
+A uni-channel has a kind, a direction, a name and an underlying backend
+object. The kind is one of @racket['async], @racket['place] or @racket['port].
+The direction is one of @racket['input], @racket['output] or
+@racket['bidirectional]. Receiving is supported for input and bidirectional
+channels. Sending is supported for output and bidirectional channels.
+
+A uni-channel that supports receiving is itself a synchronizable event:
+
+@racketblock[(sync ch)]
+
+For output-only channels, synchronizing on the uni-channel uses
+@racket[never-evt].
+
+@section{Constructors}
+
+@defproc[(make-uni-channel [backend any/c]
+                              [#:kind kind (or/c 'auto 'async 'place 'port) 'auto]
+                              [#:direction direction (or/c 'auto 'input 'output 'bidirectional) 'auto]
+                              [#:name name any/c #f])
+         uni-channel?]{
+Wraps an existing backend channel. With @racket['auto], the kind is inferred from
+@racket[async-channel?], @racket[place-channel?] or @racket[port-channel?].
+
+For a @racket[port-channel?] backend, the direction is read from
+@racket[port-channel-direction]. A single port-channel endpoint is therefore
+input-only or output-only. Use @racket[make-uni-port-channel] when one uni
+channel should combine an input port and an output port into a bidirectional
+endpoint.}
+
+@defproc[(make-uni-async-channel [ch async-channel? (make-async-channel)]
+                                    [#:direction direction (or/c 'auto 'input 'output 'bidirectional) 'bidirectional]
+                                    [#:name name any/c 'async-channel])
+         uni-channel?]{
+Wraps a single asynchronous channel. The same underlying queue is used for both
+sending and receiving when the direction is @racket['bidirectional].}
+
+@defproc[(make-uni-async-channel-pair [#:name-a name-a any/c 'async-channel-a]
+                                         [#:name-b name-b any/c 'async-channel-b])
+         (values uni-channel? uni-channel?)]{
+Creates two bidirectional uni-channel endpoints backed by two asynchronous channels.
+A value sent on the first endpoint is received on the second endpoint, and the
+other way around.}
+
+@defproc[(make-uni-place-channel [ch place-channel?]
+                                    [#:direction direction (or/c 'auto 'input 'output 'bidirectional) 'bidirectional]
+                                    [#:name name any/c 'place-channel])
+         uni-channel?]{
+Wraps an existing place-channel endpoint. Values sent through this backend must
+satisfy Racket's place-message constraints.}
+
+@defproc[(make-uni-place-channel-pair [#:name-a name-a any/c 'place-channel-a]
+                                         [#:name-b name-b any/c 'place-channel-b])
+         (values uni-channel? uni-channel?)]{
+Creates two bidirectional uni-channel endpoints using @racket[place-channel].}
+
+@defproc[(make-uni-port-channel [#:input in (or/c #f input-port?) #f]
+                                  [#:output out (or/c #f output-port?) #f]
+                                  [#:source source any/c 'port-channel]
+                                  [#:close? close? any/c #t]
+                                  [#:name name any/c 'port-channel])
+         uni-channel?]{
+Creates a uni-channel backed by one or two @racketmodname[port-channel]
+endpoints. At least one of @racket[#:input] or @racket[#:output] must be
+provided. With both, the result is bidirectional: receives come from the input
+port-channel and sends go to the output port-channel.}
+
+@section{Predicates and accessors}
+
+@defproc[(uni-channel? [v any/c]) boolean?]{Returns true when @racket[v] is a uni-channel.}
+@defproc[(uni-channel-kind [ch uni-channel?]) (or/c 'async 'place 'port)]{Returns the backend kind.}
+@defproc[(uni-channel-direction [ch uni-channel?]) (or/c 'input 'output 'bidirectional)]{Returns the channel direction.}
+@defproc[(uni-channel-name [ch uni-channel?]) any/c]{Returns the diagnostic name supplied when the uni-channel was created.}
+@defproc[(uni-channel-impl [ch uni-channel?]) any/c]{Returns the underlying backend object.}
+
+@section{Sending and receiving}
+
+@defproc[(uni-channel-put [ch uni-channel?] [v any/c]) void?]{
+Sends @racket[v] on @racket[ch]. The channel must be output-capable. For
+@racket['port] channels, the value must be serializable by @racket[serialize].
+For @racket['place] channels, the value must be allowed as a place message.}
+
+@defproc[(uni-channel-send [ch uni-channel?] [v any/c]) void?]{Alias for @racket[uni-channel-put].}
+@defproc[(uni-channel-get [ch uni-channel?]) any/c]{Receives the next value from @racket[ch].}
+@defproc[(uni-channel-recv [ch uni-channel?]) any/c]{Alias for @racket[uni-channel-get].}
+@defproc[(uni-channel-try-get [ch uni-channel?]) any/c]{Attempts to receive a value without blocking. Returns @racket[#f] when no value is currently available.}
+@defproc[(uni-channel-get-evt [ch uni-channel?]) evt?]{Returns a synchronizable receive event.}
+@defproc[(uni-channel-put-evt [ch uni-channel?] [v any/c]) evt?]{Returns an event that sends @racket[v] when selected.}
+
+@section{Closing}
+
+@defproc[(uni-channel-close [ch uni-channel?]) void?]{
+Closes @racket[ch]. For async-channel and place-channel backends this marks the
+uni-channel wrapper as closed; Racket does not provide a native close operation for
+those channel types. For port-channel backends this delegates to
+@racket[close-port-channel]. For a bidirectional port channel only the output
+side is closed, so already queued values can still be received from the input
+side until end-of-file.}
+
+@defproc[(uni-channel-closed? [ch uni-channel?]) boolean?]{Returns true when @racket[uni-channel-close] has been called on the wrapper.}
+
+@section{Port-channel errors}
+
+@defproc[(uni-channel-error-get [ch uni-channel?]) any/c]{Blocks until a backend error is available. This is meaningful for @racket['port] channels and raises an exception for backends that do not have an error channel.}
+@defproc[(uni-channel-error-try-get [ch uni-channel?]) any/c]{Attempts to get a backend error without blocking. Returns @racket[#f] when no error is available.}
+@defproc[(uni-channel-error-evt [ch uni-channel?]) evt?]{Returns a synchronizable backend-error event. For non-port backends this is @racket[never-evt].}
+
+@section{Examples}
+
+@subsection{Async-channel pair}
+
+@racketblock[
+(require uni-channel)
+
+(define-values (a b) (make-uni-async-channel-pair))
+(uni-channel-send a '(hello from a))
+(uni-channel-recv b)
+]
+
+@subsection{Place-channel pair}
+
+@racketblock[
+(require uni-channel)
+
+(define-values (a b) (make-uni-place-channel-pair))
+(uni-channel-send a '(hello from a))
+(sync b)
+]
+
+@subsection{Port-channel over a pipe}
+
+@racketblock[
+(require uni-channel)
+
+(define-values (in out) (make-pipe))
+(define ch (make-uni-port-channel #:input in #:output out))
+
+(uni-channel-send ch '(hello 1 2 3))
+(uni-channel-recv ch)
+]

test/main.rkt

@@ -0,0 +1,65 @@
+#lang racket/base
+
+(require rackunit
+         racket/async-channel
+         racket/serialize
+         port-channel
+         uni-channel)
+
+(serializable-struct msg (id payload) #:transparent)
+
+(test-case "single async channel"
+  (define ch (make-uni-async-channel #:name 'single))
+  (check-true (uni-channel? ch))
+  (check-equal? (uni-channel-kind ch) 'async)
+  (uni-channel-put ch 'hello)
+  (check-equal? (uni-channel-get ch) 'hello)
+  (check-false (uni-channel-try-get ch))
+  (sync (uni-channel-put-evt ch 'via-evt))
+  (check-equal? (sync ch) 'via-evt)
+  (uni-channel-close ch)
+  (check-true (uni-channel-closed? ch))
+  (check-exn exn:fail? (lambda () (uni-channel-put ch 'after-close))))
+
+(test-case "async channel pair"
+  (define-values (a b) (make-uni-async-channel-pair))
+  (uni-channel-send a '(from a))
+  (uni-channel-send b '(from b))
+  (check-equal? (uni-channel-recv b) '(from a))
+  (check-equal? (uni-channel-recv a) '(from b)))
+
+(test-case "place channel pair"
+  (define-values (a b) (make-uni-place-channel-pair))
+  (uni-channel-send a '(place a))
+  (check-equal? (uni-channel-recv b) '(place a))
+  (uni-channel-send b '(place b))
+  (check-equal? (sync a) '(place b)))
+
+(test-case "port channel over pipe"
+  (define-values (in out) (make-pipe))
+  (define ch (make-uni-port-channel #:input in #:output out #:source 'pipe-test #:name 'pipe))
+  (check-equal? (uni-channel-kind ch) 'port)
+  (check-equal? (uni-channel-direction ch) 'bidirectional)
+  (uni-channel-put ch '(hello 1 2 3))
+  (uni-channel-put ch (msg 7 '(a b c)))
+  (check-equal? (uni-channel-get ch) '(hello 1 2 3))
+  (check-equal? (uni-channel-get ch) (msg 7 '(a b c)))
+  (uni-channel-close ch)
+  (check-true (uni-channel-closed? ch))
+  (check-true (eof-object? (uni-channel-get ch))))
+
+(test-case "wrap existing port-channel endpoints"
+  (define-values (in out) (make-pipe))
+  (define reader (make-port-channel in #:source 'reader))
+  (define writer (make-port-channel out #:source 'writer))
+  (define in-ch (make-uni-channel reader #:name 'reader))
+  (define out-ch (make-uni-channel writer #:name 'writer))
+  (check-equal? (uni-channel-direction in-ch) 'input)
+  (check-equal? (uni-channel-direction out-ch) 'output)
+  (uni-channel-put out-ch 'wrapped)
+  (check-equal? (uni-channel-get in-ch) 'wrapped)
+  (uni-channel-close out-ch)
+  (check-true (eof-object? (uni-channel-get in-ch))))
+
+(module+ main
+  (displayln "uni-channel tests ok"))