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newt/src/Lib/LiftWhere.newt

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module Lib.LiftWhere
import Prelude
import Lib.Common
import Lib.Types
import Lib.TopContext
import Lib.Ref2
import Data.SortedMap
import Monad.State
import Data.IORef
-- track depth and whether we need to replace Bnd with a top level call
LiftEnv : U
LiftEnv = List (Maybe (QName × Nat))
liftWhereTm : {{Ref2 Defs St}} QName LiftEnv Tm M Tm
liftWhereTm name env (Lam fc nm icit quant t) =
Lam fc nm icit quant <$> liftWhereTm name (Nothing :: env) t
liftWhereTm name env (App fc t u) =
App fc <$> liftWhereTm name env t <*> liftWhereTm name env u
liftWhereTm name env (Pi fc nm icit quant t u) = do
t <- liftWhereTm name env t
u <- liftWhereTm name (Nothing :: env) u
pure $ Pi fc nm icit quant t u
liftWhereTm name env (Let fc nm v sc) = do
v <- liftWhereTm name env v
sc <- liftWhereTm name (Nothing :: env) sc
pure $ Let fc nm v sc
liftWhereTm name env tm@(Case fc t alts) = do
t <- liftWhereTm name env t
alts' <- traverse liftWhereAlt alts
pure $ Case fc t alts'
where
-- This is where I wish I had put indexes on things
liftWhereAlt : CaseAlt M CaseAlt
liftWhereAlt (CaseDefault tm) = CaseDefault <$> liftWhereTm name env tm
liftWhereAlt (CaseLit l tm) = CaseLit l <$> liftWhereTm name env tm
liftWhereAlt (CaseCons qn args tm) =
CaseCons qn args <$> liftWhereTm name (map (const Nothing) args ++ env) tm
-- This is where the magic happens
liftWhereTm name env (LetRec fc nm ty t u) = do
let l = length env
-- FIXME we need a namespace and a name, these collide everywhere.
qn <- getName name nm
let env' = (Just (qn, S l) :: env)
-- environment should subst this function (see next case)
t' <- liftWhereTm qn env' t
-- TODO we could have subst in this var and dropped the extra argument
modifyRef Defs (updateMap qn (Fn $ wrapLam (S l) t'))
-- The rest
u' <- liftWhereTm qn env' u
pure $ LetRec fc nm (Erased fc) (Erased fc) u'
where
getName : QName String M QName
getName qn@(QN ns nm) ext = do
let qn' = QN ns (nm ++ "." ++ ext)
top <- getRef Defs
let (Just _) = lookupMap qn' top | _ => pure qn'
getName qn (ext ++ "'")
-- Hacky - CompileExp expects a pi type that matches arity
wrapPi : Nat Tm Tm
wrapPi Z tm = tm
wrapPi (S k) tm = Pi fc "_" Explicit Many (Erased fc) $ wrapPi k tm
wrapLam : Nat Tm Tm
wrapLam Z tm = tm
-- REVIEW We've already erased, hopefully we don't need quantity
wrapLam (S k) tm = Lam fc "_" Explicit Many $ wrapLam k tm
-- And where it lands
liftWhereTm name env tm@(Bnd fc k) = case getAt (cast k) env of
Just (Just (qn, v)) => pure $ apply (length' env) (cast v) (Ref fc qn)
_ => pure tm
where
apply : Int Int Tm Tm
apply l 0 tm = tm
-- (l - k) is like lvl2ix, but witih k one bigger
apply l k tm = App fc (apply l (k - 1) tm) (Bnd fc (l - k))
liftWhereTm name env tm = pure tm
liftWhereFn : {{Ref2 Defs St}} QName × Def M Unit
liftWhereFn (name, Fn tm) = do
tm' <- liftWhereTm name Nil tm
modifyRef Defs $ updateMap name (Fn tm')
-- updateDef name fc type (Fn tm')
liftWhereFn _ = pure MkUnit
liftWhere : {{Ref2 Defs St}} M Unit
liftWhere = do
defs <- getRef Defs
ignore $ traverse liftWhereFn $ toList defs