mers_lib to 0.5.0, readme updated

mers_lib/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mers_lib"
-version = "0.4.0"
+version = "0.5.0"
 edition = "2021"
 license = "MIT OR Apache-2.0"
 description = "library to use the mers language in other projects"

mers_lib/README.md

@@ -3,5 +3,47 @@
 The library behind [mers](https://github.com/Dummi26/mers).
 
 With this, you can parse, compile, check and run mers code.
-
 You can also add your own functions and types which can then be used from mers, if you really want to.
+
+## Running mers
+
+There are four steps to running mers code.
+The examples show you how to actually implement them,
+this readme only explains what they do any why.
+
+### 1. Parsing
+
+This first step converts the source code, a string, to a parsed mers statement.
+
+In this step, syntax errors and unknown variables are caught.
+
+### 2. Compiling
+
+This converts a parsed mers statement to a compiled one. It almost never produces an error.
+
+### 3. Checking
+
+This step is optional. If you parse and compile your source code, you can (try to) run it.
+However, mers assumes that all mers code you run is actually valid,
+so if you don't check your codes validity, mers will probably panic while running your code.
+
+This step performs all the type-checking and determines the output type of your code, if it is valid.
+
+For example, the following code is valid and has the return type `Int/Float`:
+
+```
+my_condition := true
+
+if my_condition {
+  5
+} else {
+  1.4
+}
+```
+
+### 4. Running
+
+This step assumes that the code it is running is actually valid, so it never returns an error.
+As long as `check` didn't return an error in Step 3, it is safe to assume that this will return the value produced by the code.
+We can also assume that the return value has a type which is included in that determined by `check`.
+If `check` returned an error, this will likely panic.

mers_lib/examples/01_user_scripts.rs

@@ -35,23 +35,14 @@ fn main() -> Result<(), CheckError> {
     Ok(())
 }
 
+/// example 00
 fn parse_compile_check_run(src: String) -> Result<(Type, Data), CheckError> {
-    // prepare the string for parsing
     let mut source = Source::new_from_string(src);
-    // this is used for error messages
     let srca = Arc::new(source.clone());
-    // parse the code
     let parsed = parse(&mut source, &srca)?;
-    // get infos
     let (mut i1, mut i2, mut i3) = Config::new().bundle_std().infos();
-    // compile
     let compiled = parsed.compile(&mut i1, CompInfo::default())?;
-    // check (this step is optional, but if it is skipped when it would have returned an error, `run` will likely panic)
     let output_type = compiled.check(&mut i3, None)?;
-    // run
     let output_value = compiled.run(&mut i2);
-    // check that the predicted output type was correct
-    assert!(output_value.get().as_type().is_included_in(&output_type));
-    // return the produced value
     Ok((output_type, output_value))
 }

mers_lib/src/data/function.rs

@@ -23,6 +23,18 @@ pub struct Function {
     )>,
 }
 impl Function {
+    pub fn new(
+        out: impl Fn(&Type) -> Result<Type, CheckError> + Send + Sync + 'static,
+        run: impl Fn(Data) -> Data + Send + Sync + 'static,
+    ) -> Self {
+        Self {
+            info: Arc::new(crate::info::Info::neverused()),
+            info_check: Arc::new(Mutex::new(crate::info::Info::neverused())),
+            out: Arc::new(move |a, _| out(a)),
+            run: Arc::new(move |a, _| run(a)),
+            inner_statements: None,
+        }
+    }
     pub fn with_info_run(&self, info: Arc<Info>) -> Self {
         Self {
             info,