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teekaytaiteekaytai
authoredNov 17, 2021
Implement arity (#1170)
* Added arity test cases * Implement arity * Added arity doc * Updated environment snapshots * Prettied src\stdlib\__tests__\.misc.ts * Updated arity test snapshots * Updated arity to handle Closures
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v1.0.23v1.0.21
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‎docs/lib/misc.js

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Original file line numberDiff line numberDiff line change
@@ -159,3 +159,11 @@ function stringify(v) {
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*/
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function char_at(s, i) {}
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/**
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* Returns the number of parameters the given function <CODE>f</CODE> expects,
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* excluding the rest parameter.
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* @param {function} f - given function
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* @returns {number} number of parameters f expects
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*/
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function arity(f) {
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}

‎src/__tests__/__snapshots__/environment.ts.snap

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@@ -63,6 +63,7 @@ Object {
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"Infinity": Infinity,
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"NaN": NaN,
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"apply_in_underlying_javascript": [Function],
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"arity": [Function],
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"array_length": [Function],
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"char_at": [Function],
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"display": [Function],
@@ -206,6 +207,7 @@ Object {
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"Infinity": Infinity,
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"NaN": NaN,
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"apply_in_underlying_javascript": [Function],
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"arity": [Function],
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"array_length": [Function],
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"char_at": [Function],
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"display": [Function],
@@ -303,6 +305,7 @@ Object {
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"Infinity": Infinity,
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"NaN": NaN,
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"apply_in_underlying_javascript": [Function],
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"arity": [Function],
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"array_length": [Function],
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"char_at": [Function],
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"display": [Function],
@@ -392,6 +395,7 @@ Object {
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"Infinity": Infinity,
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"NaN": NaN,
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"apply_in_underlying_javascript": [Function],
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"arity": [Function],
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"array_length": [Function],
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"char_at": [Function],
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"display": [Function],

‎src/__tests__/__snapshots__/environmentTree.ts.snap

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‎src/createContext.ts

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Original file line numberDiff line numberDiff line change
@@ -276,6 +276,7 @@ export const importBuiltins = (context: Context, externalBuiltIns: CustomBuiltIn
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defineBuiltin(context, 'is_undefined(val)', misc.is_undefined)
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defineBuiltin(context, 'parse_int(str, radix)', misc.parse_int)
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defineBuiltin(context, 'char_at(str, index)', misc.char_at)
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defineBuiltin(context, 'arity(f)', misc.arity)
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defineBuiltin(context, 'undefined', undefined)
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defineBuiltin(context, 'NaN', NaN)
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defineBuiltin(context, 'Infinity', Infinity)

‎src/stdlib/__tests__/__snapshots__/misc.ts.snap

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@@ -1,5 +1,115 @@
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// Jest Snapshot v1, https://goo.gl/fbAQLP
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exports[`arity ignores the rest parameter: expectResult 1`] = `
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Object {
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"alertResult": Array [],
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"code": "arity(display);",
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"displayResult": Array [],
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"numErrors": 0,
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"parsedErrors": "",
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"result": 1,
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"resultStatus": "finished",
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"visualiseListResult": Array [],
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}
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`;
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exports[`arity with function with parameters is ok: expectResult 1`] = `
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Object {
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"alertResult": Array [],
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"code": "arity(arity);",
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"displayResult": Array [],
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"numErrors": 0,
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"parsedErrors": "",
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"result": 1,
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"resultStatus": "finished",
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"visualiseListResult": Array [],
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}
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`;
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exports[`arity with non-function arg f throws error: expectParsedError 1`] = `
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Object {
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"alertResult": Array [],
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"code": "arity('function');",
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"displayResult": Array [],
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"numErrors": 1,
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"parsedErrors": "Line 1: Error: arity expects a function as argument",
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"result": undefined,
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"resultStatus": "error",
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"visualiseListResult": Array [],
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}
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`;
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exports[`arity with nullary function is ok: expectResult 1`] = `
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Object {
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"alertResult": Array [],
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"code": "arity(math_random);",
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"displayResult": Array [],
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"numErrors": 0,
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"parsedErrors": "",
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"result": 0,
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"resultStatus": "finished",
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"visualiseListResult": Array [],
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}
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`;
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exports[`arity with user-made function is ok: expectResult 1`] = `
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Object {
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"alertResult": Array [],
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"code": "function test(x, y) {
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return x + y;
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}
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arity(test);",
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"displayResult": Array [],
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"numErrors": 0,
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"parsedErrors": "",
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"result": 2,
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"resultStatus": "finished",
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"visualiseListResult": Array [],
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}
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`;
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exports[`arity with user-made function with rest parameter is ok: expectResult 1`] = `
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Object {
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"alertResult": Array [],
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"code": "function test(...xs) {
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return xs;
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}
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arity(test);",
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"displayResult": Array [],
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"numErrors": 0,
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"parsedErrors": "",
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"result": 0,
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"resultStatus": "finished",
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"visualiseListResult": Array [],
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}
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`;
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exports[`arity with user-made lambda function is ok: expectResult 1`] = `
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Object {
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"alertResult": Array [],
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"code": "arity(x => x);",
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"displayResult": Array [],
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"numErrors": 0,
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"parsedErrors": "",
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"result": 1,
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"resultStatus": "finished",
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"visualiseListResult": Array [],
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}
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`;
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exports[`arity with user-made nullary function is ok: expectResult 1`] = `
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Object {
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"alertResult": Array [],
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"code": "arity(() => undefined);",
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"displayResult": Array [],
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"numErrors": 0,
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"parsedErrors": "",
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"result": 0,
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"resultStatus": "finished",
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"visualiseListResult": Array [],
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}
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`;
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exports[`char_at with non nonnegative integer second argument errors: expectParsedError 1`] = `
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Object {
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"alertResult": Array [],

‎src/stdlib/__tests__/misc.ts

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Original file line numberDiff line numberDiff line change
@@ -105,3 +105,81 @@ test('char_at with valid args (but index out of bounds) returns undefined', () =
105105
`
106106
).toBe(undefined)
107107
})
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test('arity with nullary function is ok', () => {
110+
return expectResult(
111+
stripIndent`
112+
arity(math_random);
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`,
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{ chapter: 1, native: true }
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).toBe(0)
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})
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test('arity with function with parameters is ok', () => {
119+
return expectResult(
120+
stripIndent`
121+
arity(arity);
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`,
123+
{ chapter: 1, native: true }
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).toBe(1)
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})
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test('arity ignores the rest parameter', () => {
128+
return expectResult(
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stripIndent`
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arity(display);
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`,
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{ chapter: 1, native: true }
133+
).toBe(1)
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})
135+
136+
test('arity with user-made function is ok', () => {
137+
return expectResult(
138+
stripIndent`
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function test(x, y) {
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return x + y;
141+
}
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arity(test);
143+
`,
144+
{ chapter: 1, native: true }
145+
).toBe(2)
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})
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148+
test('arity with user-made lambda function is ok', () => {
149+
return expectResult(
150+
stripIndent`
151+
arity(x => x);
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`,
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{ chapter: 1, native: true }
154+
).toBe(1)
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})
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test('arity with user-made nullary function is ok', () => {
158+
return expectResult(
159+
stripIndent`
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arity(() => undefined);
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`,
162+
{ chapter: 1, native: true }
163+
).toBe(0)
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})
165+
166+
test('arity with user-made function with rest parameter is ok', () => {
167+
return expectResult(
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stripIndent`
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function test(...xs) {
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return xs;
171+
}
172+
arity(test);
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`,
174+
{ chapter: 3, native: true }
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).toBe(0)
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})
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test('arity with non-function arg f throws error', () => {
179+
return expectParsedError(
180+
stripIndent`
181+
arity('function');
182+
`,
183+
{ chapter: 1, native: true }
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).toMatchInlineSnapshot(`"Line 1: Error: arity expects a function as argument"`)
185+
})

‎src/stdlib/misc.ts

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@@ -1,3 +1,4 @@
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import Closure from '../interpreter/closure'
12
import { Context, Value } from '../types'
23
import { stringify } from '../utils/stringify'
34

@@ -109,6 +110,25 @@ export function char_at(str: string, index: number) {
109110
return str[index]
110111
}
111112

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/**
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* arity returns the number of parameters a given function `f` expects.
115+
*
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* @param f Function whose arity is to be found. Required.
117+
*
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* An error is thrown if `f` is not a function.
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*/
120+
export function arity(f: Function) {
121+
if (f instanceof Closure) {
122+
const params = f.node.params
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const hasVarArgs = params[params.length - 1]?.type === 'RestElement'
124+
return hasVarArgs ? params.length - 1 : params.length
125+
} else if (typeof f === 'function') {
126+
return f.length
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} else {
128+
throw new Error('arity expects a function as argument')
129+
}
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}
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export function get_time() {
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return new Date().getTime()
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}

‎src/transpiler/__tests__/__snapshots__/transpiled-code.ts.snap

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@@ -15,6 +15,7 @@ exports[`Ensure no name clashes 1`] = `
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const is_undefined = nativeStorage.builtins.get(\\"is_undefined\\");
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const parse_int = nativeStorage.builtins.get(\\"parse_int\\");
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const char_at = nativeStorage.builtins.get(\\"char_at\\");
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const arity = nativeStorage.builtins.get(\\"arity\\");
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const undefined = nativeStorage.builtins.get(\\"undefined\\");
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const NaN = nativeStorage.builtins.get(\\"NaN\\");
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const Infinity = nativeStorage.builtins.get(\\"Infinity\\");
@@ -131,6 +132,7 @@ Object {
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const is_undefined = nativeStorage.builtins.get(\\"is_undefined\\");
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const parse_int = nativeStorage.builtins.get(\\"parse_int\\");
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const char_at = nativeStorage.builtins.get(\\"char_at\\");
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const arity = nativeStorage.builtins.get(\\"arity\\");
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const undefined = nativeStorage.builtins.get(\\"undefined\\");
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const NaN = nativeStorage.builtins.get(\\"NaN\\");
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const Infinity = nativeStorage.builtins.get(\\"Infinity\\");

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