F

type TyName

type TmName

data Ty

data Tm

rTm1

rTm

rTy1

rTy

x

y

z

f

n

a

b

c

polyid

polyconst

polyidty

two

onePlusOne

sixfact

ctrue

twice

type Delta

type Gamma

data Ctx

emptyCtx

checkTyVar

lookupTmVar

extendTy

extendTm

tcty

typecheck

value

steps

step

evaluate