Add shorthand package name support in jpm.

Package installation checks in the package listing if
the package name is not a url. The package listsing can be specified
via switch or env variable.

auxbin/jpm

@@ -565,12 +565,24 @@ int main(int argc, const char **argv) {
     (os/shell (string `rmdir /S /Q "` cache `"`))
     (rm cache)))
 
+(def- default-pkglist (or (os/getenv "JANET_PKGLIST") "https://github.com/janet-lang/pkgs.git"))
+
 (defn install-git
   "Install a bundle from git. If the bundle is already installed, the bundle
   is reinistalled (but not rebuilt if artifacts are cached)."
-  [repotab]
+  [repotab &opt recurse]
   (def repo (if (string? repotab) repotab (repotab :repo)))
   (def tag (unless (string? repotab) (repotab :tag)))
+  # prevent infinite recursion (very unlikely, but consider 
+  # 'my-package "my-package" in the package listing)
+  (when (> (or recurse 0) 100)
+    (error "too many references resolving package url"))
+  # Handle short names
+  (unless (string/find ":" repo)
+    (install-git (dyn :pkglist default-pkglist))
+    (def pkgs (require "pkgs"))
+    (break (install-git (get-in pkgs ['packages :value (symbol repo)])
+                        (if recurse (inc recurse) 0))))
   (def cache (find-cache))
   (os/mkdir cache)
   (def id (filepath-replace repo))
@@ -832,6 +844,7 @@ Keys are:
   --compiler : C compiler to use for natives. Defaults to cc (cl on windows).
   --archiver : C compiler to use for static libraries. Defaults to ar (lib on windows).
   --linker : C linker to use for linking natives. Defaults to cc (link on windows).
+  --pkglist : URL of git repository for package listing. Defaults to $JANET_PKGLIST or https://github.com/janet-lang/pkgs.git
 
 Flags are:
   --verbose : Print shell commands as they are executed.

jpm.1

@@ -64,6 +64,10 @@ to cc.
 .BR \-\-linker=ld
 Sets the linker used to create native modules and executables.
 
+.TP
+.BR \-\-pkglist=https://github.com/janet-lang/pkgs.git
+Sets the git repository for the package listing used to resolve shorthand package names.
+
 .TP
 .BR \-\-archiver=ar
 Sets the command used for creating static libraries, use for linking into the standalone executable.
@@ -172,5 +176,11 @@ Defaults to
 The --binpath=/some/path will override this variable.
 .RE
 
+.B JANET_PKGLIST
+.RS
+The git repository URL that contains a listing of packages. This allows installing packages with shortnames, which
+is mostly a convenience. However, package dependencies can use short names, package listings
+can be used to choose a particular set of dependency versions for a whole project.
+
 .SH AUTHOR
 Written by Calvin Rose <calsrose@gmail.com>

src/core/peg.c

@@ -887,10 +887,8 @@ static uint32_t peg_compile1(Builder *b, Janet peg) {
     JanetTable *grammar = old_grammar;
     for (; i > 0 && janet_checktype(peg, JANET_KEYWORD); --i) {
         peg = janet_table_get_ex(grammar, peg, &grammar);
-        if (!grammar || janet_checktype(peg, JANET_NIL)) {
-            builder_cleanup(b);
-            janet_panicf("grammar error in %p, unknown rule", b->form);
-        }
+        if (!grammar || janet_checktype(peg, JANET_NIL))
+            peg_panic(b, "unkown rule");
         b->form = peg;
         b->grammar = grammar;
     }