SIGNATURE Environment

IMPORT Denotation COMPLETELY
IMPORT SafeNat COMPLETELY

TYPE binding == binding(key: denotation, value: safeNat)
TYPE environment == environment(bindings: seq[binding])

FUN emptyenv : environment
FUN lookup : environment ** denotation -> safeNat
FUN bind : environment ** denotation ** safeNat -> environment

FUN testenv : environment
DEF testenv == bind(bind(emptyenv,"test",ok(5)),"test2",ok(2))

FUN test1 : safeNat
DEF test1 == lookup(testenv,"test")

FUN test2 : safeNat
DEF test2 == lookup(testenv,"test2")

FUN testfail : safeNat
DEF testfail == lookup(testenv, "isnichdrin")