simple-squiggle

A restricted subset of Squiggle
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basic_usage.js (1488B)

      1 var typed = require('../typed-function');
      2 
      3 // create a typed function
      4 var fn1 = typed({
      5   'number, string': function (a, b) {
      6     return 'a is a number, b is a string';
      7   }
      8 });
      9 
     10 // create a typed function with multiple types per argument (type union)
     11 var fn2 = typed({
     12   'string, number | boolean': function (a, b) {
     13     return 'a is a string, b is a number or a boolean';
     14   }
     15 });
     16 
     17 // create a typed function with any type argument
     18 var fn3 = typed({
     19   'string, any': function (a, b) {
     20     return 'a is a string, b can be anything';
     21   }
     22 });
     23 
     24 // create a typed function with multiple signatures
     25 var fn4 = typed({
     26   'number': function (a) {
     27     return 'a is a number';
     28   },
     29   'number, boolean': function (a, b) {
     30     return 'a is a number, b is a boolean';
     31   },
     32   'number, number': function (a, b) {
     33     return 'a is a number, b is a number';
     34   }
     35 });
     36 
     37 // create a typed function from a plain function with signature
     38 function fnPlain(a, b) {
     39   return 'a is a number, b is a string';
     40 }
     41 fnPlain.signature = 'number, string';
     42 var fn5 = typed(fnPlain);
     43 
     44 // use the functions
     45 console.log(fn1(2, 'foo'));      // outputs 'a is a number, b is a string'
     46 console.log(fn4(2));             // outputs 'a is a number'
     47 
     48 // calling the function with a non-supported type signature will throw an error
     49 try {
     50   fn2('hello', 'world');
     51 }
     52 catch (err) {
     53   console.log(err.toString());
     54   // outputs:  TypeError: Unexpected type of argument.
     55   //           Expected: number or boolean, actual: string, index: 1.
     56 }