WIP
Remove print debug line
Refactor
Convert builtin funcs to untyped funcs
Refactoring internal API
Handle type conversion
Merge branch 'master' into fixbug-on-calling-non-idempotent-func

Conflicts:
	README.md
Merge pull request #10 from ToQoz/fixbug-on-calling-non-idempotent-func

Fix bug on calling non idempotent func