918d929c09
To encourage organizing code in a way that helps in understanding, I have implemented the common idiom of requiring a `main` function. In tricu and other functional languages, it is usually placed near the top of the module. The evaluator gracefully handles the situation of passing multiple files where the intermediary "library" files do not have main functions.
48 lines
2.1 KiB
Plaintext
48 lines
2.1 KiB
Plaintext
main = toSource not?
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-- Thanks to intensionality, we can inspect the structure of a given value
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-- even if it's a function. This includes lambdas which are eliminated to
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-- Tree Calculus (TC) terms during evaluation.
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-- `triage` takes four arguments: the first three represent behaviors for each
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-- structural case in Tree Calculus (Leaf, Stem, and Fork).
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-- The fourth argument is the value whose structure is inspected. By evaluating
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-- the Tree Calculus term, `triage` enables branching logic based on the term's
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-- shape, making it possible to perform structure-specific operations such as
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-- reconstructing the terms' source code representation.
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-- triage = (\leaf stem fork : t (t leaf stem) fork)
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-- Base case of a single Leaf
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sourceLeaf = t (head "t")
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-- Stem case
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sourceStem = (\convert : (\a rest :
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t (head "(") -- Start with a left parenthesis "(".
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(t (head "t") -- Add a "t"
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(t (head " ") -- Add a space.
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(convert a -- Recursively convert the argument.
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(t (head ")") rest)))))) -- Close with ")" and append the rest.
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-- Fork case
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sourceFork = (\convert : (\a b rest :
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t (head "(") -- Start with a left parenthesis "(".
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(t (head "t") -- Add a "t"
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(t (head " ") -- Add a space.
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(convert a -- Recursively convert the first arg.
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(t (head " ") -- Add another space.
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(convert b -- Recursively convert the second arg.
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(t (head ")") rest)))))))) -- Close with ")" and append the rest.
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-- Wrapper around triage
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toSource_ = y (\self arg :
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triage
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sourceLeaf -- `triage` "a" case, Leaf
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(sourceStem self) -- `triage` "b" case, Stem
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(sourceFork self) -- `triage` "c" case, Fork
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arg) -- The term to be inspected
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-- toSource takes a single TC term and returns a String
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toSource = \v : toSource_ v ""
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exampleOne = toSource true -- OUT: "(t t)"
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exampleTwo = toSource not? -- OUT: "(t (t (t t) (t t t)) (t t (t t t)))"
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