FEATURE: change inspect to eval

Also make it easier to use by having sane defaults for the arguments.

README.md

@@ -32,17 +32,21 @@ Running ucg help will show the following output.
 Universal Configuration Grammar compiler.
 
 USAGE:
-    ucg [SUBCOMMAND]
+    ucg [FLAGS] [SUBCOMMAND]
 
 FLAGS:
-    -h, --help       Prints help information
+    -h, --help         Prints help information
-    -V, --version    Prints version information
+        --no-strict    Turn off strict checking.
+    -V, --version      Prints version information
 
 SUBCOMMANDS:
-    build       Build a specific ucg file.
+    build         Build a list of ucg files.
-    help        Prints this message or the help of the given subcommand(s)
+    converters    list the available converters
-    inspect     Inspect a specific symbol in a ucg file.
+    env           Describe the environment variables ucg uses.
-    test        Check a specific ucg file for errors.
+    eval          Evaluate an expression with an optional ucg file as context.
+    help          Prints this message or the help of the given subcommand(s)
+    importers     list the available importers for includes
+    test          Check a list of ucg files for errors and run test assertions.
 ```
 
 ## Compiling

src/main.rs

@@ -37,11 +37,11 @@ fn do_flags<'a, 'b>() -> clap::App<'a, 'b> {
             (author: crate_authors!())
             (about: "Universal Configuration Grammar compiler.")
             (@arg nostrict: --("no-strict") "Turn off strict checking.")
-            (@subcommand inspect =>
+            (@subcommand eval =>
-             (about: "Inspect a specific symbol in a ucg file.")
+             (about: "Evaluate an expression with an optional ucg file as context.")
-             (@arg expr: --expr +takes_value +required "Specify a specific binding in the ucg file to output.")
+             (@arg expr: --expr -e +takes_value +required "Expression to evaluate.")
-             (@arg target: --format +required +takes_value "Inspect output type. (flags, json, env, exec)")
+             (@arg target: --format +takes_value "Output type. (flags, json, env, exec) defaults to json.")
-             (@arg INPUT: +required "Input ucg file to inspect symbol from.")
+             (@arg INPUT: "ucg file to use as context for the expression.")
             )
             (@subcommand build =>
              (about: "Build a list of ucg files.")
@@ -244,9 +244,9 @@ fn inspect_command(
     registry: &ConverterRegistry,
     strict: bool,
 ) {
-    let file = matches.value_of("INPUT").unwrap();
+    let file = matches.value_of("INPUT").unwrap_or("std/functional.ucg");
     let sym = matches.value_of("expr");
-    let target = matches.value_of("target").unwrap();
+    let target = matches.value_of("target").unwrap_or("json");
     let mut builder =
         build::FileBuilder::new(std::env::current_dir().unwrap(), import_paths, cache);
     builder.set_strict(strict);
@@ -282,17 +282,20 @@ fn inspect_command(
                 Some(value) => {
                     // We use None here because we always output to stdout for an inspect.
                     run_converter(converter, value, None).unwrap();
-                    eprintln!("Build successful");
+                    println!("");
                     process::exit(0);
                 }
                 None => {
-                    eprintln!("Build results in no value.");
+                    eprintln!("No value.");
                     process::exit(1);
                 }
             }
         }
         None => {
-            eprintln!("No such converter {}", target);
+            eprintln!(
+                "No such format {}\nrun `ucg converters` to see available formats.",
+                target
+            );
             process::exit(1);
         }
     }
@@ -448,7 +451,7 @@ fn main() {
     } else {
         true
     };
-    if let Some(matches) = app_matches.subcommand_matches("inspect") {
+    if let Some(matches) = app_matches.subcommand_matches("eval") {
         inspect_command(matches, &import_paths, cache, &registry, strict);
     } else if let Some(matches) = app_matches.subcommand_matches("build") {
         build_command(matches, &import_paths, cache, &registry, strict);