tricu

An interpreted language for exploring Tree Calculus
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a1d060c00dae207ae61cdbfb15027a585cd650e748b83cf5b5c231f02fe5e1b7.tri (2171B)

      1 !import prelude *
      2 !export *
      3 
      4 main = toSource not?
      5 -- Thanks to intensionality, we can inspect the structure of a given value
      6 -- even if it's a function. This includes lambdas which are eliminated to
      7 -- Tree Calculus (TC) terms during evaluation.
      8 
      9 -- `triage` takes four arguments: the first three represent behaviors for each 
     10 -- structural case in Tree Calculus (Leaf, Stem, and Fork).
     11 -- The fourth argument is the value whose structure is inspected. By evaluating 
     12 -- the Tree Calculus term, `triage` enables branching logic based on the term's 
     13 -- shape, making it possible to perform structure-specific operations such as
     14 -- reconstructing the terms' source code representation.
     15 -- triage = (\leaf stem fork : t (t leaf stem) fork)
     16 
     17 -- Base case of a single Leaf
     18 sourceLeaf = t (head "t")
     19 
     20 -- Stem case
     21 sourceStem = convert : (a rest :
     22   t (head "(")                       -- Start with a left parenthesis "(".
     23     (t (head "t")                    -- Add a "t"
     24       (t (head " ")                  -- Add a space.
     25         (convert a                   -- Recursively convert the argument.
     26           (t (head ")") rest)))))   -- Close with ")" and append the rest.
     27 
     28 -- Fork case
     29 sourceFork = convert : (a b rest :
     30   t (head "(")                           -- Start with a left parenthesis "(".
     31     (t (head "t")                        -- Add a "t"
     32       (t (head " ")                      -- Add a space.
     33         (convert a                       -- Recursively convert the first arg.
     34           (t (head " ")                  -- Add another space.
     35             (convert b                   -- Recursively convert the second arg.
     36               (t (head ")") rest))))))) -- Close with ")" and append the rest.
     37 
     38 -- Wrapper around triage 
     39 toSource_ = y (self arg :
     40   triage
     41     sourceLeaf        -- `triage` "a" case, Leaf
     42     (sourceStem self) -- `triage` "b" case, Stem
     43     (sourceFork self) -- `triage` "c" case, Fork
     44     arg)              -- The term to be inspected
     45 
     46 -- toSource takes a single TC term and returns a String
     47 toSource = v : toSource_ v ""
     48 
     49 exampleOne = toSource true -- OUT: "(t t)"
     50 exampleTwo = toSource not? -- OUT: "(t (t (t t) (t t t)) (t t (t t t)))"