- + Errors (5)
 |-- z.idr line 12 col 10:
 |   When checking type of Main.getExpr:
 |   No such variable Expr
 |-- z.idr line 15 col 9:
 |   When checking type of Main.betaEq:
 |   No such variable Expr
 |-- z.idr line 13 col 2:
 |   No type declaration for Main.getExpr
 |-- z.idr line 16 col 2:
 |   No type declaration for Main.betaEq
 `-- z.idr line 28 col 17:
     When checking type of Main.App:
     No such variable getExpr

--------------------- code below ------------------------
import Data.Vect

||| Constant Types
data ANTConst = I Int | BI Integer | Fl Double | Ch Char | Str String

mutual
  ||| Context
  ||| @n total number of vars
  data ANTContext : {n : Nat} -> Type where
    AddVar : (ctx : ANTContext {n}) -> Expr ctx -> ANTContext {n=(S n)}

  getExpr : ANTContext -> Fin n -> Expr ctx
  getExpr ctx n = ?getExpr_rhs

  betaEq : Expr ctx -> Expr ctx -> Type
  betaEq = ?x

  ||| This represents when a context implies something. It is laid out
  ||| as the basic rules of the type theory system
  ||| Taken from https://eb.host.cs.st-andrews.ac.uk/drafts/impldtp.pdf page 11
  data Expr : ANTContext -> Type where
    |||     G |- f : (x : S) -> T   G |- s : S
    ||| App ----------------------------------
    |||     G |- f s : T[s/x]
    App : (ctx : ANTContext {n})
      -> (fInd : Fin n)
      -> (sInd : Fin n)
      -> ?betaEq (getExpr ctx fInd) (getExpr ctx sInd)
      -> Expr ctx
    |||     G;\x:S |- e : T   G |- (x : S) -> T : Type(n)
    ||| Lam ---------------------------------------------
    |||     G |- \x:S.e : (x : S) -> T
    ||| Given a context, an arg type within that context, and an expression
    ||| that uses that var, returns a Lam (variable name not specified
    ||| since we are using DeBrujin indexes)
    Lam : (ctx : ANTContext) -> (argType : Expr ctx)
      -> Expr (AddVar ctx argType) -> Expr ctx