dispatch.ml isn't a specific enough name

[sgrove]

I have a dispatch.ml file in my project, and while trying out webmachine I lost a bunch of time trying to figure out why I was getting this error:

$ make
ocamlbuild -use-ocamlfind -pkgs aws,conduit.mirage,containers,functoria.runtime,js_of_ocaml,js_of_ocaml.ocamlbuild,js_of_ocaml.ppx,lambdasoup,lwt.syntax,magic-mime,mirage-clock-unix,mirage-console.unix,mirage-fs-unix,mirage-http,mirage-net-macosx,mirage-types.lwt,mirage.runtime,nocrypto.lwt,omd,opium,sequence,sexplib,tcpip.arpv4,tcpip.ethif,tcpip.ipv4,tcpip.stack-direct,tcpip.tcp,tcpip.udp,tls.mirage,tyxml,webmachine -tags "syntax(camlp4o),annot,bin_annot,strict_sequence,principal,thread" -tag-line "<static*.*>: -syntax(camlp4o)" -cflag -g -lflags -g,-linkpkg -I liquid -use-menhir -plugin-tag "package(js_of_ocaml.ocamlbuild)" main.native
Warning: option -plugin-tag(s) has no effect in absence of plugin file "myocamlbuild.ml"
+ ocamlfind ocamlc -c -g -annot -bin-annot -safe-string -short-paths -principal -keep-locs -thread -strict-sequence -w +A-4-6-9-40-42-44-48 -package webmachine -package tyxml -package tls.mirage -package tcpip.udp -package tcpip.tcp -package tcpip.stack-direct -package tcpip.ipv4 -package tcpip.ethif -package tcpip.arpv4 -package sexplib -package sequence -package opium -package omd -package nocrypto.lwt -package mirage.runtime -package mirage-types.lwt -package mirage-net-macosx -package mirage-http -package mirage-fs-unix -package mirage-console.unix -package mirage-clock-unix -package magic-mime -package lwt.syntax -package lambdasoup -package js_of_ocaml.ppx -package js_of_ocaml.ocamlbuild -package js_of_ocaml -package functoria.runtime -package containers -package conduit.mirage -package aws -syntax camlp4o -I liquid -o key_gen.cmo key_gen.ml
findlib: [WARNING] Interface dispatch.cmi occurs in several directories: ., /Users/s/.opam/riseos/lib/dispatch
+ ocamlfind ocamlc -c -g -annot -bin-annot -principal -thread -strict-sequence -package webmachine -package tyxml -package tls.mirage -package tcpip.udp -package tcpip.tcp -package tcpip.stack-direct -package tcpip.ipv4 -package tcpip.ethif -package tcpip.arpv4 -package sexplib -package sequence -package opium -package omd -package nocrypto.lwt -package mirage.runtime -package mirage-types.lwt -package mirage-net-macosx -package mirage-http -package mirage-fs-unix -package mirage-console.unix -package mirage-clock-unix -package magic-mime -package lwt.syntax -package lambdasoup -package js_of_ocaml.ppx -package js_of_ocaml.ocamlbuild -package js_of_ocaml -package functoria.runtime -package containers -package conduit.mirage -package aws -syntax camlp4o -I liquid -o main.cmo main.ml
findlib: [WARNING] Interface dispatch.cmi occurs in several directories: ., /Users/s/.opam/riseos/lib/dispatch
+ ocamlfind ocamlc -c -g -annot -bin-annot -safe-string -short-paths -principal -keep-locs -thread -strict-sequence -w +A-4-6-9-40-42-44-48 -package webmachine -package tyxml -package tls.mirage -package tcpip.udp -package tcpip.tcp -package tcpip.stack-direct -package tcpip.ipv4 -package tcpip.ethif -package tcpip.arpv4 -package sexplib -package sequence -package opium -package omd -package nocrypto.lwt -package mirage.runtime -package mirage-types.lwt -package mirage-net-macosx -package mirage-http -package mirage-fs-unix -package mirage-console.unix -package mirage-clock-unix -package magic-mime -package lwt.syntax -package lambdasoup -package js_of_ocaml.ppx -package js_of_ocaml.ocamlbuild -package js_of_ocaml -package functoria.runtime -package containers -package conduit.mirage -package aws -syntax camlp4o -I liquid -o liquid/liquid.cmo liquid/liquid.ml
findlib: [WARNING] Interface dispatch.cmi occurs in several directories: ., /Users/s/.opam/riseos/lib/dispatch
+ ocamlfind ocamlopt -c -g -annot -bin-annot -safe-string -short-paths -principal -keep-locs -thread -strict-sequence -w +A-4-6-9-40-42-44-48 -package webmachine -package tyxml -package tls.mirage -package tcpip.udp -package tcpip.tcp -package tcpip.stack-direct -package tcpip.ipv4 -package tcpip.ethif -package tcpip.arpv4 -package sexplib -package sequence -package opium -package omd -package nocrypto.lwt -package mirage.runtime -package mirage-types.lwt -package mirage-net-macosx -package mirage-http -package mirage-fs-unix -package mirage-console.unix -package mirage-clock-unix -package magic-mime -package lwt.syntax -package lambdasoup -package js_of_ocaml.ppx -package js_of_ocaml.ocamlbuild -package js_of_ocaml -package functoria.runtime -package containers -package conduit.mirage -package aws -syntax camlp4o -I liquid -o key_gen.cmx key_gen.ml
findlib: [WARNING] Interface dispatch.cmi occurs in several directories: ., /Users/s/.opam/riseos/lib/dispatch
+ ocamlfind ocamlopt -c -g -annot -bin-annot -safe-string -short-paths -principal -keep-locs -thread -strict-sequence -w +A-4-6-9-40-42-44-48 -package webmachine -package tyxml -package tls.mirage -package tcpip.udp -package tcpip.tcp -package tcpip.stack-direct -package tcpip.ipv4 -package tcpip.ethif -package tcpip.arpv4 -package sexplib -package sequence -package opium -package omd -package nocrypto.lwt -package mirage.runtime -package mirage-types.lwt -package mirage-net-macosx -package mirage-http -package mirage-fs-unix -package mirage-console.unix -package mirage-clock-unix -package magic-mime -package lwt.syntax -package lambdasoup -package js_of_ocaml.ppx -package js_of_ocaml.ocamlbuild -package js_of_ocaml -package functoria.runtime -package containers -package conduit.mirage -package aws -syntax camlp4o -I liquid -o liquid/liquid.cmx liquid/liquid.ml
findlib: [WARNING] Interface dispatch.cmi occurs in several directories: ., /Users/s/.opam/riseos/lib/dispatch
+ ocamlfind ocamlopt -c -g -annot -bin-annot -safe-string -short-paths -principal -keep-locs -thread -strict-sequence -w +A-4-6-9-40-42-44-48 -package webmachine -package tyxml -package tls.mirage -package tcpip.udp -package tcpip.tcp -package tcpip.stack-direct -package tcpip.ipv4 -package tcpip.ethif -package tcpip.arpv4 -package sexplib -package sequence -package opium -package omd -package nocrypto.lwt -package mirage.runtime -package mirage-types.lwt -package mirage-net-macosx -package mirage-http -package mirage-fs-unix -package mirage-console.unix -package mirage-clock-unix -package magic-mime -package lwt.syntax -package lambdasoup -package js_of_ocaml.ppx -package js_of_ocaml.ocamlbuild -package js_of_ocaml -package functoria.runtime -package containers -package conduit.mirage -package aws -syntax camlp4o -I liquid -o dispatch.cmx dispatch.ml
findlib: [WARNING] Interface dispatch.cmi occurs in several directories: ., /Users/s/.opam/riseos/lib/dispatch
File "dispatch.ml", line 354, characters 2-55:
Warning 7: the method allowed_methods is overridden.
File "dispatch.ml", line 1:
Error: The files /Users/s/.opam/riseos/lib/webmachine/webmachine.cmi
       and dispatch.cmi make inconsistent assumptions over interface Dispatch
Command exited with code 2.
Compilation unsuccessful after building 12 targets (0 cached) in 00:00:01.
make: *** [main.native] Error 10

Turns out that because there's a dispatch.ml here and one in my project, they can't coexist.

A fuller name for this project would be nice since dispatch is likely to be used in lots of other places too.

[seliopou]

@sgrove making what we discussed public and closing the issue.

Seems like this is a transient issue in the process of porting. I imagine that for the most part, utility libraries won't use dispatch. Instead, applications will either use dispatch or webmachine directly as the single way to do path-based dispatching.