diff --git a/semantic-core/src/Data/Core.hs b/semantic-core/src/Data/Core.hs
index 7ff8dc307..75a4a9473 100644
--- a/semantic-core/src/Data/Core.hs
+++ b/semantic-core/src/Data/Core.hs
@@ -11,6 +11,7 @@ module Data.Core
 , block
 , ann
 , annWith
+, instantiate
 ) where
 
 import Control.Applicative (Alternative (..))
@@ -139,3 +140,7 @@ gfoldT var let' seq' lam app unit bool if' string load edge frame dot assign ann
 -- | Bind occurrences of a name in a 'Core' term, producing a 'Core' in which the name is bound.
 bind :: Eq a => a -> Core a -> Core (Incr a)
 bind name = fmap (match name)
+
+-- | Substitute a 'Core' term for the free variable in a given 'Core', producing a closed 'Core' term.
+instantiate :: Core a -> Core (Incr a) -> Core a
+instantiate t b = b >>= subst t . fmap pure