Add constraints via Jinja expressions

engine/baml-lib/baml-core/src/ir/ir_helpers/scope_diagnostics.rs

@@ -148,4 +148,8 @@ impl ScopeStack {
  pub fn push_error(&mut self, error: String) {
  self.scopes.last_mut().unwrap().errors.push(error);
  }
+
+ pub fn push_warning(&mut self, warning: String) {
+ self.scopes.last_mut().unwrap().warnings.push(warning);
+ }
 }

engine/baml-lib/baml-core/src/ir/ir_helpers/to_baml_arg.rs

@@ -1,10 +1,13 @@
-use baml_types::{BamlMap, BamlMediaType, BamlValue, FieldType, LiteralValue, TypeValue};
+use baml_types::{
+ BamlMap, BamlValue, Constraint, ConstraintLevel, FieldType, LiteralValue, TypeValue
+};
 use core::result::Result;
 use std::path::PathBuf;
 
 use crate::ir::IntermediateRepr;
 
 use super::{scope_diagnostics::ScopeStack, IRHelper};
+use internal_baml_jinja::evaluate_predicate;
 
 #[derive(Default)]
 pub struct ParameterError {
@@ -325,6 +328,36 @@ impl ArgCoercer {
  }
  }
  }
+ FieldType::Constrained { base, constraints } => {
+ let val = self.coerce_arg(ir, base, value, scope)?;
+ for c@Constraint {
+ level,
+ expression,
+ label,
+ } in constraints.iter()
+ {
+ let constraint_ok =
+ evaluate_predicate(&val, &expression).unwrap_or_else(|err| {
+ scope.push_error(format!(
+ "Error while evaluating check {c:?}: {:?}",
+ err
+ ));
+ false
+ });
+ if !constraint_ok {
+ let msg = label.as_ref().unwrap_or(&expression.0);
+ match level {
+ ConstraintLevel::Check => {
+ scope.push_warning(format!("Failed check: {msg}"));
+ }
+ ConstraintLevel::Assert => {
+ scope.push_error(format!("Failed assert: {msg}"));
+ }
+ }
+ }
+ }
+ Ok(val)
+ }
  }
  }
 }

engine/baml-lib/baml-core/src/ir/json_schema.rs

@@ -236,6 +236,7 @@ impl<'db> WithJsonSchema for FieldType {
  }
  }
  }
+ FieldType::Constrained { base, .. } => base.json_schema(),
  }
  }
 }