1 files changed, 54 insertions, 0 deletions
diff --git a/library/src/base/mod.rs b/library/src/base/mod.rs
new file mode 100644
index 00000000..bb1c8c51
--- /dev/null
+++ b/library/src/base/mod.rs
@@ -0,0 +1,54 @@
+//! Foundational functions.
+
+mod calc;
+mod color;
+mod data;
+mod string;
+
+pub use calc::*;
+pub use color::*;
+pub use data::*;
+pub use string::*;
+
+use comemo::Track;
+use typst::model::{Eval, Route, Scopes, Vm};
+use typst::syntax::Source;
+
+use crate::prelude::*;
+
+/// The name of a value's type.
+pub fn type_(_: &mut Vm, args: &mut Args) -> SourceResult<Value> {
+    Ok(args.expect::<Value>("value")?.type_name().into())
+}
+
+/// Ensure that a condition is fulfilled.
+pub fn assert(_: &mut Vm, args: &mut Args) -> SourceResult<Value> {
+    let Spanned { v, span } = args.expect::<Spanned<bool>>("condition")?;
+    if !v {
+        bail!(span, "assertion failed");
+    }
+    Ok(Value::None)
+}
+
+/// Evaluate a string as Typst markup.
+pub fn eval(vm: &mut Vm, args: &mut Args) -> SourceResult<Value> {
+    let Spanned { v: text, span } = args.expect::<Spanned<String>>("source")?;
+
+    // Parse the source and set a synthetic span for all nodes.
+    let source = Source::synthesized(text, span);
+    let ast = source.ast()?;
+
+    // Evaluate the source.
+    let std = &vm.world.config().scope;
+    let scopes = Scopes::new(Some(std));
+    let route = Route::default();
+    let mut sub = Vm::new(vm.world, route.track(), None, scopes);
+    let result = ast.eval(&mut sub);
+
+    // Handle control flow.
+    if let Some(flow) = sub.flow {
+        bail!(flow.forbidden());
+    }
+
+    Ok(Value::Content(result?))
+}