GitLab

use writer monad to avoid rebindable syntax

See merge request !1

make final type checkers for record, variant and fo-recursive types more systematic (case, inferNormed, requiredNormed)

flip lattice upside down and use glb for aggregation for record types to match the aggregation operator of infer

introduction of languages for Products and Records and type checker for Records including test (not all test cases succeed)

change lookup function (has ITerm as toplevel to distinguish between cases and other parts of the language (ExpTerm)