Add more advanced configuration options to modules.ini and support

automatically downloading and installing from it.

26 files changed, 229 insertions, 286 deletions

diff --git a/CHANGES.md b/CHANGES.md
index f071f7fa..3e3ac7c9 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,8 @@
 
 - Added a versioning system based on `CHANGES.md` files and `modules.ini`
   configuration for module aliases.
+- When attempting to run a program with a module that is not installed, Tomo
+  can prompt the user to automatically install it.
 - Programs can use `--version` as a CLI flag to print a Tomo program's version
   number and exit.
 - Added `tomo --prefix` to print the Tomo install prefix.
diff --git a/Makefile b/Makefile
index e5baef93..c00d9bf4 100644
--- a/Makefile
+++ b/Makefile
@@ -179,8 +179,7 @@ man/man1/tomo.1: docs/tomo.1.md
 
 examples:
 	./local-tomo -qIL examples/log examples/ini examples/vectors examples/http examples/wrap examples/colorful
-	./local-tomo -e examples/game/game.tm examples/http-server/http-server.tm \
-		examples/tomodeps/tomodeps.tm examples/tomo-install/tomo-install.tm
+	./local-tomo -e examples/game/game.tm examples/http-server/http-server.tm
 	./local-tomo examples/learnxiny.tm
 
 deps:
diff --git a/docs/libraries.md b/docs/libraries.md
index 37f8ee05..8457b67a 100644
--- a/docs/libraries.md
+++ b/docs/libraries.md
@@ -171,9 +171,9 @@ path where the library is installed, so if the library `foo` has version
 `v1.2`, then it will be installed to
 `~/.local/share/tomo_vX.Y/installed/foo_v1.2/`. When using a library, you must
 explicitly supply either the exact version in the `use` statement like this:
-`use foo_v1.2`, or provide a `modules.ini` file that lists shorthand aliases
-for the libraries you're using alongside the files that use them. The syntax
-is a simple `alias=full_name` format on each line. Here is an example:
+`use foo_v1.2`, or provide a `modules.ini` file that lists version information
+and other details about modules being used. For each module, you should provide
+a `[modulename]` section with a `version=` field.
 
 ```tomo
 # File: foo.tm
@@ -184,10 +184,34 @@ use mylib
 And the accompanying `modules.ini`:
 
 ```ini
-mylib=mylib_v1.2
+[mylib]
+version=v1.2
 ```
 
 The `modules.ini` file must be in the same directory as the source files that
 use its aliases, so if you want to share a `modules.ini` file across multiple
 subdirectories, use a symbolic link.
 
+### Module Downloading
+
+If you want, you can also provide the following options for a module:
+
+- `git`: a Git URL to clone the repository
+- `revision`: if a Git URL is provided, use this revision
+- `url`: a URL to download an archive of the library (`.zip`, `.tar`, `.tar.gz`)
+- `path`: if the library is provided in a subdirectory of the repository or
+  archive, list the subdirectory here.
+
+For example, this is what it would look like to use the `colorful` library that
+is distributed with the Tomo compiler in the `examples/colorful` subdirectory:
+
+```ini
+[colorful]
+version=v1.0
+git=git@github.com:bruce-hill/tomo
+path=examples/colorful
+```
+
+If this extra information is provided, Tomo will prompt the user to ask if they
+want to download and install this module automatically when they run a program
+and don't have the necessary module installed.
diff --git a/docs/versions.md b/docs/versions.md
index db7a1036..c68d1f81 100644
--- a/docs/versions.md
+++ b/docs/versions.md
@@ -70,8 +70,8 @@ version number will be used to determine its installation location and how it's
 used in code. You must either explicitly import the library with its version
 number (e.g. `use foo_v1.2`) or include a `modules.ini` configuration file that
 maps a shorthand alias to a specific version of a library. For example, if the
-`modules.ini` file has `foo=foo_v1.2`, you can put `use foo` to use v1.2 of the
-`foo` library (assuming you have it installed).
+`modules.ini` file has a `[foo]` section with `version=v1.2`, you can put `use
+foo` to use v1.2 of the `foo` library (assuming you have it installed).
 
 # Rationale
 
diff --git a/examples/README.md b/examples/README.md
index 2b5f81fa..9e9291e5 100644
--- a/examples/README.md
+++ b/examples/README.md
@@ -8,8 +8,6 @@ This folder contains some example programs and libraries.
   style of [learnxinyminutes.com](https://learnxinyminutes.com/).
 - [game](game/): An example game using raylib.
 - [http-server](http-server/): A multithreaded HTTP server.
-- [tomodeps](tomodeps/): A library for finding Tomo dependencies.
-- [tomo-install](tomo-install/): A library for installing Tomo dependencies.
 - [wrap](wrap/): A command-line program to wrap text.
 
 ## Example Libraries
diff --git a/examples/colorful/README.md b/examples/colorful/README.md
index 04a221e3..faded9b1 100644
--- a/examples/colorful/README.md
+++ b/examples/colorful/README.md
@@ -54,8 +54,14 @@ colorful [--help] [texts...] [--by-line] [--files ...]
 
 `colorful` can also be used as a Tomo library:
 
+```ini
+# modules.ini
+[colorful]
+version=v1.0
+```
+
 ```tomo
-use colorful_v1.0
+use colorful
 
 $Colorful"
     @(blue:Welcome to the @(bold:party)!)
diff --git a/examples/colorful/colorful.tm b/examples/colorful/colorful.tm
index 270efe8c..9a8bbbba 100644
--- a/examples/colorful/colorful.tm
+++ b/examples/colorful/colorful.tm
@@ -7,7 +7,7 @@ HELP := "
 
 CSI := "\033["
 
-use patterns_v1.0
+use patterns
 
 lang Colorful
     convert(text:Text -> Colorful)
diff --git a/examples/colorful/modules.ini b/examples/colorful/modules.ini
new file mode 100644
index 00000000..fb52a859
--- /dev/null
+++ b/examples/colorful/modules.ini
@@ -0,0 +1,2 @@
+[patterns]
+version=v1.0
diff --git a/examples/coroutines/README.md b/examples/coroutines/README.md
index 86b5dd00..644c0e07 100644
--- a/examples/coroutines/README.md
+++ b/examples/coroutines/README.md
@@ -5,8 +5,14 @@ This is a coroutine library built on top of a modified version of
 
 ## Example Usage
 
+```ini
+# modules.ini
+[coroutines]
+version=v1.0
+```
+
 ```tomo
-use coroutines_v1.0
+use coroutines
 
 func main()
     co := Coroutine(func()
diff --git a/examples/http-server/connection-queue.tm b/examples/http-server/connection-queue.tm
index 5cf8bb91..c56069e1 100644
--- a/examples/http-server/connection-queue.tm
+++ b/examples/http-server/connection-queue.tm
@@ -1,4 +1,4 @@
-use pthreads_v1.0
+use pthreads
 
 func _assert_success(name:Text, val:Int32; inline)
     fail("$name() failed!") if val < 0
diff --git a/examples/http-server/http-server.tm b/examples/http-server/http-server.tm
index 717aa733..89141c32 100644
--- a/examples/http-server/http-server.tm
+++ b/examples/http-server/http-server.tm
@@ -9,9 +9,9 @@ use <unistd.h>
 use <arpa/inet.h>
 use <err.h>
 
-use commands_v1.0
-use pthreads_v1.0
-use patterns_v1.0
+use commands
+use pthreads
+use patterns
 
 use ./connection-queue.tm
 
@@ -138,7 +138,7 @@ func load_routes(directory:Path -> {Text=RouteEntry})
 func main(directory:Path, port=Int32(8080))
     say("Serving on port $port")
     routes := load_routes(directory)
-    say(" Hosting: $routes")
+    say("Hosting: $routes")
 
     serve(port, func(request:HTTPRequest)
         if handler := routes[request.path]
diff --git a/examples/http-server/modules.ini b/examples/http-server/modules.ini
new file mode 100644
index 00000000..171e11d2
--- /dev/null
+++ b/examples/http-server/modules.ini
@@ -0,0 +1,8 @@
+[pthreads]
+version=v1.0
+
+[patterns]
+version=v1.0
+
+[commands]
+version=v1.0
diff --git a/examples/http-server/sample-site/random.tm b/examples/http-server/sample-site/random.tm
index 75e185b3..153ac2af 100755
--- a/examples/http-server/sample-site/random.tm
+++ b/examples/http-server/sample-site/random.tm
@@ -1,5 +1,5 @@
 #!/bin/env tomo
-use random_v1.0
+use random
 
 func main()
     say("
diff --git a/examples/ini/ini.tm b/examples/ini/ini.tm
index 9bcfb3a4..4dc27725 100644
--- a/examples/ini/ini.tm
+++ b/examples/ini/ini.tm
@@ -1,5 +1,5 @@
 
-use patterns_v1.0
+use patterns
 
 _USAGE := "
     Usage: ini <filename> "[section[/key]]"
diff --git a/examples/ini/modules.ini b/examples/ini/modules.ini
new file mode 100644
index 00000000..fb52a859
--- /dev/null
+++ b/examples/ini/modules.ini
@@ -0,0 +1,2 @@
+[patterns]
+version=v1.0
diff --git a/examples/tomo-install/CHANGES.md b/examples/tomo-install/CHANGES.md
deleted file mode 100644
index 42ae752c..00000000
--- a/examples/tomo-install/CHANGES.md
+++ /dev/null
@@ -1,5 +0,0 @@
-# Version History
-
-## v1.0
-
-Initial version
diff --git a/examples/tomo-install/tomo-install.tm b/examples/tomo-install/tomo-install.tm
deleted file mode 100644
index e9838859..00000000
--- a/examples/tomo-install/tomo-install.tm
+++ /dev/null
@@ -1,84 +0,0 @@
-use shell_v1.0
-use patterns_v1.0
-
-_USAGE := "
-    tomo-install file.tm...
-"
-
-_HELP := "
-    tomo-install: a tool for installing libraries for the Tomo language
-    Usage: $_USAGE
-"
-
-func find_urls(path:Path -> [Text])
-    urls : @[Text]
-    if path.is_directory()
-        for f in path.children()
-            urls.insert_all(find_urls(f))
-    else if path.is_file() and path.extension() == ".tm"
-        for line in path.by_line()!
-            if captures := line.pattern_captures($Pat/use{space}{url}/) or line.pattern_captures($Pat/{id}{space}:={space}use{space}{url}/)
-                urls.insert(captures[-1])
-    return urls
-
-func main(paths:[Path])
-    if paths.length == 0
-        paths = [(./)]
-
-    urls := (++: find_urls(p) for p in paths) or []
-
-    github_token := (~/.config/tomo/github-token).read()
-
-    (~/.local/share/tomo/installed).create_directory()
-    (~/.local/share/tomo/lib).create_directory()
-
-    for url in urls
-        original_url := url
-        url_without_protocol := url.trim_pattern($Pat"http{0-1 s}://", right=no)
-        hash := $Shell@(echo -n @url_without_protocol | sha256sum).get_output()!.slice(to=32)
-        if (~/.local/share/tomo/installed/$hash).is_directory()
-            say("Already installed: $url")
-            skip
-
-        alias : Text?
-        curl_flags := ["-L"]
-        if github := url_without_protocol.pattern_captures($Pat"github.com/{!/}/{!/}#{..}")
-            user := github[1]
-            repo := github[2]
-            tag := github[3]
-            url = "https://api.github.com/repos/$user/$repo/tarball/$tag"
-            alias = "$(repo.without_prefix("tomo-")).$(tag).$(user)"
-            if github_token
-                curl_flags ++= ["-H", "Authorization: Bearer $github_token"]
-            curl_flags ++= [
-                "-H", "Accept: application/vnd.github+json",
-                "-H", "X-GitHub-Api-Version: 2022-11-28",
-            ]
-
-        (~/.local/share/tomo/downloads/$hash).create_directory()
-        say($Shell@`
-            set -euo pipefail
-            cd ~/.local/share/tomo/downloads/@hash
-            curl @curl_flags @url | tar xz -C ~/.local/share/tomo/installed --strip-components=1 --one-top-level=@hash
-            echo @original_url > ~/.local/share/tomo/installed/@hash/source.url
-            tomo -L ~/.local/share/tomo/installed/@hash
-            if [ "`uname -s`" = "Darwin" ]; then
-                ln -f -s ../installed/@hash/lib@hash.dylib ~/.local/share/tomo/lib/lib@hash.dylib
-            else
-                ln -f -s ../installed/@hash/lib@hash.so ~/.local/share/tomo/lib/lib@hash.so
-            fi
-        `.get_output()!)
-
-        if alias
-            say($Shell(
-                set -exuo pipefail
-                ln -f -s @hash ~/.local/share/tomo/installed/@alias
-                if [ "`uname -s`" = "Darwin" ]; then
-                    ln -f -s lib@hash.dylib ~/.local/share/tomo/lib/lib@alias.dylib
-                else
-                    ln -f -s lib@hash.so ~/.local/share/tomo/lib/lib@alias.so
-                fi
-            ).get_output()!)
-        
-        say("\[1]Installed $url!\[]")
-                
diff --git a/examples/tomodeps/CHANGES.md b/examples/tomodeps/CHANGES.md
deleted file mode 100644
index 42ae752c..00000000
--- a/examples/tomodeps/CHANGES.md
+++ /dev/null
@@ -1,5 +0,0 @@
-# Version History
-
-## v1.0
-
-Initial version
diff --git a/examples/tomodeps/tomodeps.tm b/examples/tomodeps/tomodeps.tm
deleted file mode 100644
index af7f2573..00000000
--- a/examples/tomodeps/tomodeps.tm
+++ /dev/null
@@ -1,117 +0,0 @@
-# Show a Tomo dependency graph
-
-use patterns_v1.0
-
-_USAGE := "Usage: tomodeps <files...>"
-
-_HELP := "
-    tomodeps: Show a file dependency graph for Tomo source files.
-    $_USAGE
-"
-
-enum Dependency(File(path:Path), Module(name:Text))
-
-func _get_file_dependencies(file:Path -> |Dependency|)
-    if not file.is_file()
-        say("Could not read file: $file")
-        return ||
-
-    deps : @|Dependency|
-    if lines := file.by_line()
-        for line in lines
-            if line.matches_pattern($Pat/use {..}.tm/)
-                file_import := Path.from_text(line.replace_pattern($Pat/use {..}/, "@1")).resolved(relative_to=file)
-                deps.add(Dependency.File(file_import))
-            else if line.matches_pattern($Pat/use {id}/)
-                module_name := line.replace_pattern($Pat/use {..}/, "@1")
-                deps.add(Dependency.Module(module_name))
-    return deps[]
-
-func _build_dependency_graph(dep:Dependency, dependencies:@{Dependency=|Dependency|})
-    return if dependencies.has(dep)
-
-    dependencies[dep] = || # Placeholder
-
-    dep_deps := when dep is File(path)
-        _get_file_dependencies(path)
-    is Module(module)
-        dir := (~/.local/share/tomo/installed/$module)
-        module_deps : @|Dependency|
-        visited : @|Path|
-        unvisited := @|f.resolved() for f in dir.files() if f.extension() == ".tm"|
-        while unvisited.length > 0
-            file := unvisited.items[-1]
-            unvisited.remove(file)
-            visited.add(file)
-
-            for file_dep in _get_file_dependencies(file)
-                when file_dep is File(f)
-                    if not visited.has(f)
-                        unvisited.add(f)
-                is Module(m)
-                    module_deps.add(file_dep)
-        module_deps[]
-
-    dependencies[dep] = dep_deps
-
-    for dep2 in dep_deps
-        _build_dependency_graph(dep2, dependencies)
-
-func get_dependency_graph(dep:Dependency -> {Dependency=|Dependency|})
-    graph : @{Dependency=|Dependency|}
-    _build_dependency_graph(dep, graph)
-    return graph
-
-func _printable_name(dep:Dependency -> Text)
-    when dep is Module(module)
-        return "\[34;1]$module\[]"
-    is File(f)
-        f = f.relative_to((.))
-        if f.exists()
-            return Text(f)
-        else
-            return "\[31;1]$f (not found)\[]"
-
-func _draw_tree(dep:Dependency, dependencies:{Dependency=|Dependency|}, already_printed:@|Dependency|, prefix="", is_last=yes)
-    if already_printed.has(dep)
-        say(prefix ++ (if is_last then "└── " else "├── ") ++ _printable_name(dep) ++ " \[2](recursive)\[]")
-        return
-
-    say(prefix ++ (if is_last then "└── " else "├── ") ++ _printable_name(dep))
-    already_printed.add(dep)
-    
-    child_prefix := prefix ++ (if is_last then "    " else "│   ")
-    
-    children := dependencies[dep] or ||
-    for i,child in children.items
-        is_child_last := (i == children.length)
-        _draw_tree(child, dependencies, already_printed, child_prefix, is_child_last)
-
-func draw_tree(dep:Dependency, dependencies:{Dependency=|Dependency|})
-    printed : @|Dependency|
-    say(_printable_name(dep))
-    printed.add(dep)
-    deps := dependencies[dep] or ||
-    for i,child in deps.items
-        is_child_last := (i == deps.length)
-        _draw_tree(child, dependencies, already_printed=printed, is_last=is_child_last)
-
-func main(files:[Text])
-    if files.length == 0
-        exit("
-            Please provide at least one file!
-            $_USAGE
-        ")
-
-    for arg in files
-        if arg.matches_pattern($Pat/{..}.tm/)
-            path := Path.from_text(arg).resolved()
-            dependencies := get_dependency_graph(File(path))
-            draw_tree(File(path), dependencies)
-        else if arg.matches_pattern($Pat/{id}/)
-            dependencies := get_dependency_graph(Module(arg))
-            draw_tree(Module(arg), dependencies)
-        else
-            say("\[2]Skipping $arg\[]")
-            skip
-
diff --git a/src/compile.c b/src/compile.c
index cd6aef72..2ecb8c9e 100644
--- a/src/compile.c
+++ b/src/compile.c
@@ -12,6 +12,7 @@
 #include "cordhelpers.h"
 #include "enums.h"
 #include "environment.h"
+#include "modules.h"
 #include "parse.h"
 #include "stdlib/integers.h"
 #include "stdlib/nums.h"
@@ -1976,10 +1977,13 @@ static CORD _compile_statement(env_t *env, ast_t *ast)
             CORD suffix = get_id_suffix(Path$as_c_string(path));
             return with_source_info(env, ast, CORD_all("$initialize", suffix, "();\n"));
         } else if (use->what == USE_MODULE) {
-            const char *name = module_alias(ast);
+            module_info_t mod = get_module_info(ast);
             glob_t tm_files;
-            if (glob(String(TOMO_PREFIX"/share/tomo_"TOMO_VERSION"/installed/", name, "/[!._0-9]*.tm"), GLOB_TILDE, NULL, &tm_files) != 0)
-                code_err(ast, "Could not find library");
+            const char *folder = mod.version ? String(mod.name, "_", mod.version) : mod.name;
+            if (glob(String(TOMO_PREFIX"/share/tomo_"TOMO_VERSION"/installed/", folder, "/[!._0-9]*.tm"), GLOB_TILDE, NULL, &tm_files) != 0) {
+                if (!try_install_module(mod))
+                    code_err(ast, "Could not find library");
+            }
 
             CORD initialization = CORD_EMPTY;
 
@@ -4485,10 +4489,13 @@ CORD compile_statement_type_header(env_t *env, Path_t header_path, ast_t *ast)
         Path_t build_dir = Path$resolved(Path$parent(header_path), Path$current_dir());
         switch (use->what) {
         case USE_MODULE: {
-            const char *name = module_alias(ast);
+            module_info_t mod = get_module_info(ast);
             glob_t tm_files;
-            if (glob(String(TOMO_PREFIX"/share/tomo_"TOMO_VERSION"/installed/", name, "/[!._0-9]*.tm"), GLOB_TILDE, NULL, &tm_files) != 0)
-                code_err(ast, "Could not find library");
+            const char *folder = mod.version ? String(mod.name, "_", mod.version) : mod.name;
+            if (glob(String(TOMO_PREFIX"/share/tomo_"TOMO_VERSION"/installed/", folder, "/[!._0-9]*.tm"), GLOB_TILDE, NULL, &tm_files) != 0) {
+                if (!try_install_module(mod))
+                    code_err(ast, "Could not find library");
+            }
 
             CORD includes = CORD_EMPTY;
             for (size_t i = 0; i < tm_files.gl_pathc; i++) {
diff --git a/src/environment.c b/src/environment.c
index 4fdfbd4e..05ebed5a 100644
--- a/src/environment.c
+++ b/src/environment.c
@@ -7,12 +7,8 @@
 #include "cordhelpers.h"
 #include "environment.h"
 #include "parse.h"
-#include "stdlib/c_strings.h"
 #include "stdlib/datatypes.h"
-#include "stdlib/memory.h"
 #include "stdlib/paths.h"
-#include "stdlib/pointers.h"
-#include "stdlib/simpleparse.h"
 #include "stdlib/tables.h"
 #include "stdlib/text.h"
 #include "stdlib/util.h"
@@ -793,40 +789,4 @@ void set_binding(env_t *env, const char *name, type_t *type, CORD code)
     Table$str_set(env->locals, name, new(binding_t, .type=type, .code=code));
 }
 
-const char *module_alias(ast_t *use)
-{
-    static Table_t cache = {};
-    const char **cached = Table$get(cache, &use, Table$info(Pointer$info("@", &Memory$info), &CString$info));
-    if (cached) return *cached;
-    const char *name = Match(use, Use)->path;
-    const char *alias = name;
-    if (streq(name, "commands")) alias = "commands_v1.0";
-    else if (streq(name, "random")) alias = "random_v1.0";
-    else if (streq(name, "base64")) alias = "base64_v1.0";
-    else if (streq(name, "core")) alias = "core_v1.0";
-    else if (streq(name, "patterns")) alias = "patterns_v1.0";
-    else if (streq(name, "pthreads")) alias = "pthreads_v1.0";
-    else if (streq(name, "shell")) alias = "shell_v1.0";
-    else if (streq(name, "time")) alias = "time_v1.0";
-    else if (streq(name, "uuid")) alias = "uuid_v1.0";
-    else {
-        Path_t alias_file = Path$sibling(Path$from_str(use->file->filename), Text("modules.ini"));
-        OptionalClosure_t by_line = Path$by_line(alias_file);
-        if (by_line.fn) {
-            OptionalText_t (*next_line)(void*) = by_line.fn;
-            for (Text_t line; (line=next_line(by_line.userdata)).length >= 0; ) {
-                char *line_str = Text$as_c_string(line);
-                const char *line_alias = NULL, *full_version = NULL;
-                if (!strparse(line_str, &line_alias, "=", &full_version)
-                    && streq(line_alias, name)) {
-                        alias = full_version;
-                        break;
-                }
-            }
-        }
-    }
-    Table$set(&cache, &use, &alias, Table$info(Pointer$info("@", &Memory$info), &CString$info));
-    return alias;
-}
-
 // vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1,\:0
diff --git a/src/environment.h b/src/environment.h
index 474bab61..a89935e6 100644
--- a/src/environment.h
+++ b/src/environment.h
@@ -94,6 +94,5 @@ binding_t *get_namespace_binding(env_t *env, ast_t *self, const char *name);
 extern type_t *TEXT_TYPE;
 extern type_t *PATH_TYPE;
 extern type_t *PATH_TYPE_TYPE;
-const char *module_alias(ast_t *use);
 
 // vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1,\:0
diff --git a/src/modules.c b/src/modules.c
new file mode 100644
index 00000000..71e33eec
--- /dev/null
+++ b/src/modules.c
@@ -0,0 +1,121 @@
+#include "modules.h"
+#include "stdlib/memory.h"
+#include "stdlib/paths.h"
+#include "stdlib/simpleparse.h"
+#include "stdlib/pointers.h"
+#include "stdlib/tables.h"
+#include "stdlib/text.h"
+#include "stdlib/types.h"
+
+#define xsystem(...) ({ int _status = system(String(__VA_ARGS__)); if (!WIFEXITED(_status) || WEXITSTATUS(_status) != 0) errx(1, "Failed to run command: %s", String(__VA_ARGS__)); })
+
+module_info_t get_module_info(ast_t *use)
+{
+    static Table_t cache = {};
+    TypeInfo_t *cache_type = Table$info(Pointer$info("@", &Memory$info), Pointer$info("@", &Memory$info));
+    module_info_t **cached = Table$get(cache, &use, cache_type);
+    if (cached) return **cached;
+    const char *name = Match(use, Use)->path;
+    module_info_t *info = new(module_info_t, .name=name);
+    if (streq(name, "commands")) info->version = "v1.0";
+    else if (streq(name, "random")) info->version = "v1.0";
+    else if (streq(name, "base64")) info->version = "v1.0";
+    else if (streq(name, "core")) info->version = "v1.0";
+    else if (streq(name, "patterns")) info->version = "v1.0";
+    else if (streq(name, "pthreads")) info->version = "v1.0";
+    else if (streq(name, "shell")) info->version = "v1.0";
+    else if (streq(name, "time")) info->version = "v1.0";
+    else if (streq(name, "uuid")) info->version = "v1.0";
+    else {
+        Path_t alias_file = Path$sibling(Path$from_str(use->file->filename), Text("modules.ini"));
+        OptionalClosure_t by_line = Path$by_line(alias_file);
+        if (by_line.fn) {
+            OptionalText_t (*next_line)(void*) = by_line.fn;
+          find_section:;
+            for (Text_t line; (line=next_line(by_line.userdata)).length >= 0; ) {
+                char *line_str = Text$as_c_string(line);
+                if (line_str[0] == '[' && strncmp(line_str+1, name, strlen(name)) == 0
+                    && line_str[1+strlen(name)] == ']')
+                    break;
+            }
+            for (Text_t line; (line=next_line(by_line.userdata)).length >= 0; ) {
+                char *line_str = Text$as_c_string(line);
+                if (line_str[0] == '[') goto find_section;
+                if (!strparse(line_str, "version=", &info->version)
+                    || !strparse(line_str, "url=", &info->url)
+                    || !strparse(line_str, "git=", &info->git)
+                    || !strparse(line_str, "path=", &info->path)
+                    || !strparse(line_str, "revision=", &info->revision))
+                    continue;
+            }
+        }
+    }
+    Table$set(&cache, &use, &info, cache_type);
+    return *info;
+
+}
+
+bool try_install_module(module_info_t mod)
+{
+    if (mod.git) {
+        OptionalText_t answer = ask(
+            Texts(Text("The module \""), Text$from_str(mod.name), Text("\" is not installed.\nDo you want to install it from git URL "),
+                  Text$from_str(mod.git), Text("? [Y/n] ")),
+            true, true);
+        if (!(answer.length == 0 || Text$equal_values(answer, Text("Y")) || Text$equal_values(answer, Text("y"))))
+            return false;
+        print("Installing ", mod.name, " from git...");
+        Path_t tmpdir = Path$unique_directory(Path("/tmp/tomo-module-XXXXXX"));
+        if (mod.revision) xsystem("git clone --depth=1 --revision ", mod.revision, " ", mod.git, " ", tmpdir);
+        else xsystem("git clone --depth=1 ", mod.git, " ", tmpdir);
+        if (mod.path) xsystem("tomo -IL ", tmpdir, "/", mod.path);
+        else xsystem("tomo -IL ", tmpdir);
+        Path$remove(tmpdir, true);
+        return true;
+    } else if (mod.url) {
+        OptionalText_t answer = ask(
+            Texts(Text("The module "), Text$from_str(mod.name), Text(" is not installed.\nDo you want to install it from URL "),
+                  Text$from_str(mod.url), Text("? [Y/n] ")),
+            true, true);
+        if (!(answer.length == 0 || Text$equal_values(answer, Text("Y")) || Text$equal_values(answer, Text("y"))))
+            return false;
+
+        print("Installing ", mod.name, " from URL...");
+
+        const char *p = strrchr(mod.url, '/');
+        if (!p) return false;
+        const char *filename = p + 1;
+        p = strchr(filename, '.');
+        if (!p) return false;
+        const char *extension = p + 1;
+        Path_t tmpdir = Path$unique_directory(Path("/tmp/tomo-module-XXXXXX"));
+        xsystem("curl ", mod.url, " -o ", tmpdir);
+        if (streq(extension, ".zip"))
+            xsystem("unzip ", tmpdir, "/", filename);
+        else if (streq(extension, ".tar.gz") || streq(extension, ".tar"))
+            xsystem("tar xf ", tmpdir, "/", filename);
+        else
+            return false;
+        const char *basename = String(string_slice(filename, strcspn(filename, ".")));
+        if (mod.path) xsystem("tomo -IL ", tmpdir, "/", basename, "/", mod.path);
+        else xsystem("tomo -IL ", tmpdir, "/", basename);
+        Path$remove(tmpdir, true);
+        return true;
+    } else if (mod.path) {
+        OptionalText_t answer = ask(
+            Texts(Text("The module "), Text$from_str(mod.name), Text(" is not installed.\nDo you want to install it from path "),
+                  Text$from_str(mod.path), Text("? [Y/n] ")),
+            true, true);
+        if (!(answer.length == 0 || Text$equal_values(answer, Text("Y")) || Text$equal_values(answer, Text("y"))))
+            return false;
+
+        print("Installing ", mod.name, " from path...");
+        xsystem("tomo -IL ", mod.path);
+        return true;
+    }
+
+    return false;
+}
+
+
+// vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1,\:0
diff --git a/src/modules.h b/src/modules.h
new file mode 100644
index 00000000..36b05d3d
--- /dev/null
+++ b/src/modules.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <stdbool.h>
+
+#include "ast.h"
+
+typedef struct {
+    const char *name, *version, *url, *git, *revision, *path;
+} module_info_t;
+
+module_info_t get_module_info(ast_t *use);
+bool try_install_module(module_info_t mod);
+
+// vim: ts=4 sw=0 et cino=L2,l1,(0,W4,m1,\:0
diff --git a/src/tomo.c b/src/tomo.c
index a2ccc84a..b47cd8e1 100644
--- a/src/tomo.c
+++ b/src/tomo.c
@@ -16,6 +16,7 @@
 #include "ast.h"
 #include "compile.h"
 #include "cordhelpers.h"
+#include "modules.h"
 #include "parse.h"
 #include "stdlib/bools.h"
 #include "stdlib/bytes.h"
@@ -614,14 +615,15 @@ void build_file_dependency_graph(Path_t path, Table_t *to_compile, Table_t *to_l
             break;
         }
         case USE_MODULE: {
-            const char *name = module_alias(stmt_ast);
+            module_info_t mod = get_module_info(stmt_ast);
+            const char *full_name = mod.version ? String(mod.name, "_", mod.version) : mod.name;
             Text_t lib = Texts(Text("-Wl,-rpath,'"),
-                               Text(TOMO_PREFIX "/share/tomo_"TOMO_VERSION"/installed/"), Text$from_str(name),
+                               Text(TOMO_PREFIX "/share/tomo_"TOMO_VERSION"/installed/"), Text$from_str(full_name),
                                Text("' '" TOMO_PREFIX "/share/tomo_"TOMO_VERSION"/installed/"),
-                               Text$from_str(name), Text("/lib"), Text$from_str(name), Text(SHARED_SUFFIX "'"));
+                               Text$from_str(full_name), Text("/lib"), Text$from_str(full_name), Text(SHARED_SUFFIX "'"));
             Table$set(to_link, &lib, NULL, Table$info(&Text$info, &Void$info));
 
-            List_t children = Path$glob(Path$from_str(String(TOMO_PREFIX"/share/tomo_"TOMO_VERSION"/installed/", name, "/*.tm")));
+            List_t children = Path$glob(Path$from_str(String(TOMO_PREFIX"/share/tomo_"TOMO_VERSION"/installed/", full_name, "/[!._0-9]*.tm")));
             for (int64_t i = 0; i < children.length; i++) {
                 Path_t *child = (Path_t*)(children.data + i*children.stride);
                 Table_t discarded = {.fallback=to_compile};
diff --git a/src/typecheck.c b/src/typecheck.c
index 60cef3fc..f97235b4 100644
--- a/src/typecheck.c
+++ b/src/typecheck.c
@@ -11,6 +11,7 @@
 #include "ast.h"
 #include "cordhelpers.h"
 #include "environment.h"
+#include "modules.h"
 #include "parse.h"
 #include "stdlib/paths.h"
 #include "stdlib/tables.h"
@@ -182,13 +183,16 @@ static env_t *load_module(env_t *env, ast_t *module_ast)
         return load_module_env(env, ast);
     }
     case USE_MODULE: {
-        const char *name = module_alias(module_ast);
+        module_info_t mod = get_module_info(module_ast);
         glob_t tm_files;
-        if (glob(String(TOMO_PREFIX"/share/tomo_"TOMO_VERSION"/installed/", name, "/[!._0-9]*.tm"), GLOB_TILDE, NULL, &tm_files) != 0)
-            code_err(module_ast, "Could not find library");
+        const char *folder = mod.version ? String(mod.name, "_", mod.version) : mod.name;
+        if (glob(String(TOMO_PREFIX"/share/tomo_"TOMO_VERSION"/installed/", folder, "/[!._0-9]*.tm"), GLOB_TILDE, NULL, &tm_files) != 0) {
+            if (!try_install_module(mod))
+                code_err(module_ast, "Could not find or install library");
+        }
 
         env_t *module_env = fresh_scope(env);
-        Table$str_set(env->imports, name, module_env);
+        Table$str_set(env->imports, mod.name, module_env);
 
         for (size_t i = 0; i < tm_files.gl_pathc; i++) {
             const char *filename = tm_files.gl_pathv[i];