restructure code a bit, add comparison functions for primitive types and composed types (needed to put values in sets)

compare/primitives.js

@@ -0,0 +1,29 @@
+import { Char, Double, Int } from "../primitives/types.js";
+
+export const compareNumbers = x => y => {
+  if (typeof(x) !== 'number' || typeof(y) !== 'number') {
+    throw new Error(`was only meant to compare numbers! got ${x} and ${y}`);
+  }
+  return (x < y) ? -1 : (x > y) ? 1 : 0;
+}
+
+export const compareStrings = x => y => {
+  if (typeof(x) !== 'string' || typeof(y) !== 'string') {
+    throw new Error(`was only meant to compare strings! got ${x} and ${y}`);
+  }
+  return (x < y) ? -1 : (x > y) ? 1 : 0;
+}
+
+export const compareBools = x => y => {
+  if (typeof(x) !== 'boolean' || typeof(y) !== 'boolean') {
+    throw new Error(`was only meant to compare booleans! got ${x} and ${y}`);
+  }
+  return x - y;
+};
+
+export const typeToCmp = new Map([
+  [Int, compareNumbers],
+  [Char, compareStrings],
+  [Double, compareNumbers],
+  [Boolean, compareBools],
+]);

compare/structures.js

@@ -0,0 +1,58 @@
+import { compareNumbers } from "./primitives.js"
+import { length as lengthLs } from "../structures/list.js";
+import { read, length as lengthSet } from "../structures/set.js";
+import { constructorProduct, getLeft, getRight } from "../structures/product.js";
+import { match } from "../structures/sum.js";
+
+// (a -> a -> Int) -> [a] -> [a] -> Int
+export const compareLists = compareElems => x => y => {
+  return compareNumbers(lengthLs(x))(lengthLs(y))
+    || (() => {
+      for (let i=0; i<lengthLs(x); i++) {
+        const elemCmp = compareElems(get(x)(i))(get(y)(i));
+        if (elemCmp !== 0) {
+          return elemCmp;
+        }
+      }
+      return 0;
+    })();
+};
+
+// (a -> a -> Int) -> (b -> b -> Int) -> (a, b) -> (a, b) -> Int
+export const compareProducts = compareLeft => compareRight => x => y => {
+  return compareLeft (getLeft (x))(getLeft (y))
+      || compareRight(getRight(x))(getRight(y));
+};
+
+// (a -> a -> Int) -> (b -> b -> Int) -> (a | b) -> (a | b) -> Int
+export const compareSums = compareLeft => compareRight => x => y => {
+  return match(x)(constructorProduct
+    (leftValueX => match(y)(constructorProduct
+      (leftValueY => compareLeft(leftValueX)(leftValueY))
+      ((rightValueY) => -1) // x is 'left' and y is 'right' => x < y
+    ))
+    (rightValueX => match(y)(constructorProduct
+      (leftValueY => 1) // x is 'right' and y is 'left' => x > y
+      (rightValueY => compareRight(rightValueX)(rightValueY))
+    ))
+  );
+};
+
+// (a -> a -> Int) -> {a} -> {a} -> Int
+export const compareSets = compareElems => x => y => {
+  return compareNumbers(lengthSet(x))(lengthSet(y))
+    || (() => {
+      // sets have same size -> iterate over both sets and compare their elements pairwise
+      // because of the underlying red-black tree, iteration happens in ordered fashion
+      const iterate = iterX => iterY =>
+        read(iterX)
+        (keyX => nextX =>
+          read(iterY)
+            // we could also use the comparison function that is embedded in the set object,
+            // but to be consistent with the other comparison-functions, we don't.
+            (keyY => nextY => compareElems(keyX)(keyY) || iterate(nextX)(nextY))
+            (0)) // end of set y (we'll never get here because sets are same size)
+        (0) // end of set x;
+      iterate(first(x))(first(y));
+    })();
+};

compare/versioning.js

@@ -0,0 +1,31 @@
+export const compareSlots = compareElems => slotA => slotB => {
+  if (slotA.depth < slotB.depth) {
+    return -1;
+  }
+  if (slotB.depth < slotA.depth) {
+    return 1;
+  }
+  return compareValues(compareElems)(slotA.value)(slotB.value);
+};
+
+export const compareValues = compareElems => valA => valB => {
+  if (valA.kind < valB.kind) {
+    return -1;
+  }
+  if (valB.kind < valA.kind) {
+    return 1;
+  }
+  if (valA.kind === "literal") {
+    return compareElems(valA.out)(valB.out);
+  }
+  if (valA.kind === "read") {
+    return compareSlots(compareElems)(valA.slot)(valB.slot);
+  }
+  if (valA.kind === "transformation") {
+    const cmpIn = compareValues(compareElems)(valA.in)(valB.in);
+    if (cmpIn !== 0) {
+      return cmpIn;
+    }
+    return compareValues(compareElems)(valA.fn)(valB.fn);
+  }
+};

primitives/types.js

@@ -43,5 +43,3 @@ export const ModuleSymbols = {l:[
   {i: SymbolType  , t: SymbolT},
   {i: SymbolGenericType, t: SymbolT},
 ]};
-
-

scripts/versioning.js

@@ -3,6 +3,7 @@ import { newLiteral, transform, read, getReadDependencies, verifyValue } from ".
 import { merge, merge2, newSlot, overwrite } from "../versioning/slot.js";
 import createRBTree from "functional-red-black-tree";
 import { add, emptySet, RBTreeWrapper } from "../structures/set.js";
+import { compareNumbers } from "../compare/primitives.js";
 
 const inc = x => x + 1;
 
@@ -58,14 +59,8 @@ const sixSlot   = overwrite(fiveSlot)(newLiteral(6));
 const sevenSlot = overwrite(fiveSlot)(newLiteral(7));
 const eightSlot = overwrite(fiveSlot)(newLiteral(8));
 
-const numCompare = x => y => {
-  if (typeof(x) !== 'number' || typeof(y) !== 'number') {
-    throw new Error(`was only meant to compare numbers! got ${x} and ${y}`);
-  }
-  return (x < y) ? -1 : (x > y) ? 1 : 0;
-};
-const intMerge = merge(numCompare);
-const intMerge2 = merge2(numCompare);
+const intMerge = merge(compareNumbers);
+const intMerge2 = merge2(compareNumbers);
 
 const sixSevenSlot = intMerge(sixSlot)(sevenSlot);
 const sevenEightSlot = intMerge(sevenSlot)(eightSlot);
@@ -83,13 +78,6 @@ console.log(pretty({sixSevenEightSlot}));
 // console.log("## Heterogeneous data ##");
 // console.log("########################");
 
-// const strCompare = x => y => {
-//   if (typeof(x) !== 'string' || typeof(y) !== 'string') {
-//     throw new Error(`was only meant to compare strings! got ${x} and ${y}`);
-//   }
-//   return (x < y) ? -1 : (x > y) ? 1 : 0;
-// };
-
 // // Slot<Int>
 // const numberOfSheepSlot  = newSlot(Symbol('numberOfSheep'))(newLiteral(5));
 // const alternativeNumberOfSheepSlot = newSlot(Symbol('alternativeNumberOfSheep'))(newLiteral(6));
@@ -108,7 +96,7 @@ console.log(pretty({sixSevenEightSlot}));
 //     transform(read(labelSlot))(combineFn)));
       
 // console.log(
-//   add(add(emptySet(compareSlots(strCompare)))(labelAndValueSlotA))(labelAndValueSlotB)
+//   add(add(emptySet(compareSlots(compareStrings)))(labelAndValueSlotA))(labelAndValueSlotB)
 // );
 
 // merge()(labelSlot)(labelAndValueSlot)
@@ -119,4 +107,9 @@ console.log("## RB Tree ##")
 console.log("#############")
 
 // just a small experiment
-console.log(new RBTreeWrapper(createRBTree().insert(1).insert(1).insert(2)));
+console.log(
+  createRBTree()
+  .insert(1)
+  .insert(1)
+  .insert(2)
+);

structures/list.js

@@ -6,12 +6,20 @@ import { lsType } from "./types.js";
 import { Typed } from "../typed.js"
 
 // 'normal' implementation
-const emptyList = {l:[]};
+export const emptyList = {l:[]};
 const emptyListType = makeGeneric(a => lsType(a));
-const get = ls => i => ls.l[i];
-const put = ls => i => elem => ({l: ls.l.with(Number(i), elem)});
-const push = ls => elem => ({l:ls.l.concat([elem])});
-const map = ls => fn => ({ l: ls.l.map(elem => fn(elem)) });
+export const get = ls => i => ls.l[i];
+export const put = ls => i => elem => ({l: ls.l.with(Number(i), elem)});
+export const push = ls => elem => ({l:ls.l.concat([elem])});
+export const map = ls => fn => ({ l: ls.l.map(elem => fn(elem)) });
+export const length = ls => ls.l.length;
+export const fold = ls => callback => initial => {
+  let acc = initial;
+  for (let i=0; i<ls.l.length; i++) {
+    acc = callback(acc)(ls.l[i]);
+  }
+  return acc;
+}
 
 export const String = lsType(Char); // alias
 export const Module = lsType(Typed);

structures/product.js

@@ -1,3 +1,7 @@
+// Product-type (also called: pair, tuple)
+// A Product-type always has only two fields, called "left" and "right".
+// Product-types of more fields (called Structs) can be constructed by nesting Product-types.
+
 import { makeGeneric } from "../generics/generics.js";
 import { GenericType, Type } from "../primitives/types.js";
 import { typedFnType } from "./types.js";

structures/set.js

@@ -24,6 +24,20 @@ export const emptySet = compareFn => new RBTreeWrapper(createRBTree((x, y) => co
 export const has = set => key => set.tree.get(key) === true;
 export const add = set => key => set.tree.get(key) === true ? set : new RBTreeWrapper(set.tree.insert(key, true));
 export const remove = set => key => new RBTreeWrapper(set.tree.remove(key));
+export const length = set => set.tree.length;
+
+export const first = set => set.tree.begin;
+export const last  = set => set.tree.end;
+
+// test if iterator is 'done', and if not, get element and advance iterator.
+export const read = iter => ifNotDone => ifDone => {
+  if (iter !== undefined && iter.valid) {
+    return ifNotDone(iter.key)(iter.clone().next());
+  }
+  else {
+    return ifDone();
+  }
+};
 
 export const forEach = set => fn => {
   set.tree.forEach(key => { fn(key); });

structures/struct.js

@@ -7,7 +7,10 @@ function capitalizeFirstLetter(val) {
   return String(val).charAt(0).toUpperCase() + String(val).slice(1);
 }
 
-// [{l: "x", r: Double}, {l: "y", r: Double}] => (Double × (Double × Unit))
+// 'fields' is an array of (name: string, type: Type) pairs.
+// e.g.:
+//   [{l: "x", r: Double}, {l: "y", r: Double}]
+//   results in the type (Double × (Double × Unit))
 export const structType = fields => {
   if (fields.length === 0) {
     return Unit;

structures/sum.js

@@ -1,17 +1,22 @@
+// Sum-type (also called: tagged union, disjoin union, variant type)
+// A Sum-type always has only two variants, called "left" and "right".
+// Sum-types of more variants (called Enums) can be constructed by nesting Sum-types.
+
 import { prodType } from "./types.js";
 import { GenericType, Type } from "../primitives/types.js";
 import { typedFnType } from "./types.js";
 import { makeGeneric } from "../generics/generics.js";
 import { sumType } from "./types.js";
 
-export const constructorLeft  = left  => ({variant: "L", value: left });
-export const constructorRight = right => ({variant: "R", value: right});
+export const constructorLeft  = left  => ({t: "L", v: left }); // 't': tag, 'v': value
+export const constructorRight = right => ({t: "R", v: right});
 
 // signature:
 //   sum-type -> (leftType -> resultType, rightType -> resultType) -> resultType
-export const match = sum => handlers => sum.variant === "L"
-  ? handlers.left(sum.value)
-  : handlers.right(sum.value);
+export const match = sum => handlers =>
+  sum.t === "L"
+    ? handlers.left(sum.v)
+    : handlers.right(sum.v);
 
 export const ModuleSum = {l:[
   // binary type constructor

versioning/slot.js

@@ -1,6 +1,7 @@
 import { add, emptySet, forEach } from "../structures/set.js";
 import { deepEqual } from "../util/util.js";
 import {inspect} from "node:util";
+import { compareSlots } from "../compare/versioning.js";
 
 // UUID -> Value<a> -> Slot<a>
 export const newSlot = uuid => value => ({
@@ -10,39 +11,6 @@ export const newSlot = uuid => value => ({
   [inspect.custom]: (depth, options, inspect) => `newSlot(${inspect(uuid)}, ${inspect(value)})`,
 });
 
-export const compareSlots = compareElems => slotA => slotB => {
-  if (slotA.depth < slotB.depth) {
-    return -1;
-  }
-  if (slotB.depth < slotA.depth) {
-    return 1;
-  }
-  return compareValues(compareElems)(slotA.value)(slotB.value);
-};
-
-export const compareValues = compareElems => valA => valB => {
-  if (valA.kind < valB.kind) {
-    return -1;
-  }
-  if (valB.kind < valA.kind) {
-    return 1;
-  }
-  if (valA.kind === "literal") {
-    return compareElems(valA.out)(valB.out);
-  }
-  if (valA.kind === "read") {
-    return compareSlots(compareElems)(valA.slot)(valB.slot);
-  }
-  if (valA.kind === "transformation") {
-    const cmpIn = compareValues(compareElems)(valA.in)(valB.in);
-    if (cmpIn !== 0) {
-      return cmpIn;
-    }
-    return compareValues(compareElems)(valA.fn)(valB.fn);
-  }
-};
-
-
 // Slot<a> -> Value<a> -> Slot<a>
 export const overwrite = slot => value => ({
   overwrites: slot,