tricu

An interpreted language for exploring Tree Calculus
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environment.tri (578B)

      1 !import prelude *
      2 !import io *
      3 !export *
      4 
      5 -- Environment effects: ask and local.
      6 --   ask reads the current environment value.
      7 --   local f action runs action with the env transformed by f.
      8 --
      9 --   The CLI starts with an empty (Leaf) environment.  This demo uses
     10 --   local to inject a real string so that ask returns something readable.
     11 
     12 main = io <| 
     13   (bind 
     14   local (_ : "sandbox")
     15     (bind ask (env :
     16     bind (putStrLn (append "working in env: " env)) (_ :
     17     pure "inside-done"))))
     18   (outside :
     19     bind (putStrLn (append "local returned: " outside)) (_ :
     20     pure t))