Replace substitution function with a map

It makes using variables with queries more approachable, but some work
still has to be done.
- The type `Subs` should be renamed and moved out of `Schema`, together with
`AST.Core.Value` probably.
- Some kind of conversion should be possible from a user-defined input
type T to the Value. So the final HashMap should have a type like
`HashMap name a`, where a is an instance of a potential typeclass
InputType.

1 files changed, 1 insertions, 1 deletions

diff --git a/stack.yaml b/stack.yaml
index f7d770d..2155a49 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-14.18
+resolver: lts-14.19
 
 packages:
 - .