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Use enums in typechecker
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@arnav-ag
arnav-ag committed Apr 2, 2024
1 parent 29dde0d commit ad0894c
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Showing 3 changed files with 78 additions and 74 deletions.
2 changes: 1 addition & 1 deletion src/tests/test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ export function testProgram(program: string, expectedValue: any) {
program = program.trimEnd();
let program_obj: Object = parse(program);
program_obj = { tag: 'BlockStatement', body: program_obj };
log(JSON.stringify(program_obj, null, 2));
// log(JSON.stringify(program_obj, null, 2));
const instrs = compile_program(program_obj);
checkTypes(program_obj);
let bytecode = assemble(instrs);
Expand Down
36 changes: 36 additions & 0 deletions src/utils/utils.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
export function pair(x, xs) {
return [x, xs];
}

export function array_test(x) {
if (typeof Array.isArray !== 'undefined') {
return Array.isArray(x);
} else {
return x instanceof Array;
}
}

export function is_pair(x) {
return array_test(x) && x.length === 2;
}

export function head(xs) {
if (is_pair(xs)) {
return xs[0];
} else {
throw new Error('head(xs) expects a pair as argument xs, but encountered ' + xs);
}
}

export function tail(xs) {
if (is_pair(xs)) {
return xs[1];
} else {
throw new Error('tail(xs) expects a pair as argument xs, but encountered ' + xs);
}
}

export function error(value, ...strs) {
const output = strs.length === 0 ? value : value + ' ' + strs.join(' ');
throw new Error(output);
}
114 changes: 41 additions & 73 deletions src/vm/oogavm-typechecker.ts
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Original file line number Diff line number Diff line change
@@ -1,44 +1,14 @@
import { equal } from 'assert';
import { pair, head, tail, error } from '../utils/utils.js';
import debug from 'debug';

const log = debug('ooga:typechecker');

function array_test(x) {
if (Array.isArray === undefined) {
return x instanceof Array;
} else {
return Array.isArray(x);
}
}

function pair(x, xs) {
return [x, xs];
}

function is_pair(x) {
return array_test(x) && x.length === 2;
}

function head(xs) {
if (is_pair(xs)) {
return xs[0];
} else {
throw new Error('head(xs) expects a pair as argument xs, but encountered ' + xs);
}
}

function tail(xs) {
if (is_pair(xs)) {
return xs[1];
} else {
throw new Error('tail(xs) expects a pair as argument xs, but encountered ' + xs);
}
}

function error(value, ...strs) {
const output = strs.length === 0 ? value : value + ' ' + strs.join(' ');
throw new Error(output);
}
const types = {
Any: 'Any',
Integer: 'Integer',
Boolean: 'Boolean',
String: 'String',
Null: 'Null',
};

function is_integer(x) {
return typeof x === 'number' && x % 1 === 0;
Expand All @@ -48,10 +18,6 @@ function is_boolean(x) {
return typeof x === 'boolean';
}

function is_undefined(x) {
return x === undefined;
}

function is_null(x) {
return x === null;
}
Expand All @@ -66,19 +32,19 @@ const unparse_types = t => {

const equal_type = (ts1, ts2) => {
// ts1 and ts2 can be either a string or an array of strings
// 'Any' is a special type that can be used to match any type
// types.Any is a special type that can be used to match any type
log('equal_type', ts1, ts2);
if (ts1 === ts2) {
return true;
}
if (typeof ts1 === 'string' && typeof ts2 === 'string') {
return ts1 === 'Any' || ts2 === 'Any';
return ts1 === types.Any || ts2 === types.Any;
}
if (typeof ts1 === 'string') {
return ts2.length === 1 && (ts2[0] === ts1 || ts2[0] === 'Any');
return ts2.length === 1 && (ts2[0] === ts1 || ts2[0] === types.Any);
}
if (typeof ts2 === 'string') {
return ts1.length === 1 && (ts1[0] === ts2 || ts1[0] === 'Any');
return ts1.length === 1 && (ts1[0] === ts2 || ts1[0] === types.Any);
}
if (ts1.length !== ts2.length) {
return false;
Expand All @@ -91,32 +57,32 @@ const equal_type = (ts1, ts2) => {
return true;
};

const unary_arith_type = { tag: 'Function', args: ['Integer'], res: ['Integer'] };
const unary_arith_type = { tag: 'Function', args: [types.Integer], res: [types.Integer] };

const binary_arith_type = {
tag: 'Function',
args: ['Integer', 'Integer'],
res: ['Integer'],
args: [types.Integer, types.Integer],
res: [types.Integer],
};

const number_comparison_type = {
tag: 'Function',
args: ['Integer', 'Integer'],
res: ['Boolean'],
args: [types.Integer, types.Integer],
res: [types.Boolean],
};

const binary_bool_type = {
tag: 'Function',
args: ['Boolean', 'Boolean'],
res: ['Boolean'],
args: [types.Boolean, types.Boolean],
res: [types.Boolean],
};

const unary_bool_type = { tag: 'Function', args: ['Boolean'], res: ['Boolean'] };
const unary_bool_type = { tag: 'Function', args: [types.Boolean], res: [types.Boolean] };

const binary_equal_type = {
tag: 'Function',
args: ['Any', 'Any'],
res: ['Boolean'],
args: [types.Any, types.Any],
res: [types.Boolean],
};

const global_type_frame = {
Expand All @@ -139,7 +105,7 @@ const global_type_frame = {
'++': unary_arith_type,
'--': unary_arith_type,
'==': binary_equal_type,
print: { tag: 'Function', args: ['Any'], res: ['Null'] },
print: { tag: 'Function', args: [types.Any], res: [types.Null] },
};

// A type environment is null or a pair
Expand Down Expand Up @@ -180,12 +146,13 @@ let expected_ret;
// functions for each component tag
const type_comp = {
Integer: (comp, te) =>
is_integer(comp.value) ? 'Integer' : error('expected number, got ' + comp.value),
is_integer(comp.value) ? types.Integer : error('expected number, got ' + comp.value),
Boolean: (comp, te) =>
is_boolean(comp.value) ? 'Boolean' : error('expected bool, got ' + comp.value),
is_boolean(comp.value) ? types.Boolean : error('expected bool, got ' + comp.value),
String: (comp, te) =>
is_string(comp.value) ? 'String' : error('expected string, got ' + comp.value),
Null: (comp, te) => (is_null(comp.value) ? 'Null' : error('expected null, got ' + comp.value)),
is_string(comp.value) ? types.String : error('expected string, got ' + comp.value),
Null: (comp, te) =>
is_null(comp.value) ? types.Null : error('expected null, got ' + comp.value),
Name: (comp, te) => {
log('Name');
log(JSON.stringify(comp, null, 2));
Expand Down Expand Up @@ -214,7 +181,7 @@ const type_comp = {
IfStatement: (comp, te) => {
const t0 = type(comp.test, te);
log('IfStatement: t0', t0);
if (!equal_type(t0, 'Boolean')) error('expected predicate type: Boolean, got ' + t0);
if (!equal_type(t0, types.Boolean)) error('expected predicate type: Boolean, got ' + t0);
const t1 = type(comp.consequent, te);
log('IfStatement: t1', t1);
const t2 = type(comp.alternate, te);
Expand All @@ -239,7 +206,7 @@ const type_comp = {
let ret_type = type(comp.body, new_te);
log('FunctionDeclaration: Got ret_type: ', ret_type, 'Expected ret_type: ', expected_ret);
if (ret_type?.tag !== 'ret') {
ret_type = { tag: 'ret', type: ['Null'] };
ret_type = { tag: 'ret', type: [types.Null] };
}

if (!equal_type(ret_type.type, expected_ret)) {
Expand Down Expand Up @@ -269,7 +236,7 @@ const type_comp = {
let ret_type = type(comp.body, new_te);
log('LambdaDeclaration: Got ret_type: ', ret_type, 'Expected ret_type: ', expected_ret);
if (ret_type?.tag !== 'ret') {
ret_type = { tag: 'ret', type: ['Null'] };
ret_type = { tag: 'ret', type: [types.Null] };
}

if (!equal_type(ret_type.type, expected_ret)) {
Expand Down Expand Up @@ -346,7 +313,7 @@ const type_comp = {
SequenceStatement: (comp, te) => {
log('SequenceStatement');
log(JSON.stringify(comp, null, 2));
let latest_type = 'Null';
let latest_type = types.Null;
let stmt;
let new_type;
for (let i = 0; i < comp.body.length; i++) {
Expand Down Expand Up @@ -398,7 +365,7 @@ const type_comp = {
},
ReturnStatement: (comp, te) => {
if (comp.expression === null) {
return { tag: 'ret', type: ['Null'] };
return { tag: 'ret', type: [types.Null] };
}
let ret_type = type(comp.expression, te);
if (in_func) {
Expand Down Expand Up @@ -465,20 +432,21 @@ const type_comp = {
: te;
log('ForStatement: extended_te', extended_te);
// check the test expression, this can be null as well
const t0 = comp.test ? type(comp.test, extended_te) : 'Boolean';
const t0 = comp.test ? type(comp.test, extended_te) : types.Boolean;
log('ForStatement: t0', t0);
if (!equal_type(t0, 'Boolean')) {
if (!equal_type(t0, types.Boolean)) {
error('expected predicate type: Boolean, got ' + t0);
}
// check the update expression, this can be null as well
// the update expression should either be a CallExpression or an AssignmentExpression
const t1 = comp.update ? type(comp.update, extended_te) : 'Null';

const t1 = comp.update ? type(comp.update, extended_te) : types.Null;
log('ForStatement: t1', t1);
const t2 = type(comp.body, extended_te);
return 'Null';
log('ForStatement: t2', t2);
return types.Null;
},
BreakStatement: (comp, te) => 'Null',
ContinueStatement: (comp, te) => 'Null',
BreakStatement: (comp, te) => types.Null,
ContinueStatement: (comp, te) => types.Null,
};

const type = (comp, te) => {
Expand Down

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