Merge pull request #2173 from aarroyoc/js-eval

Add js_eval/2 for wasm32

src/lib/wasm.pl

@@ -0,0 +1,29 @@
+/** Predicates for the WebAssembly platform
+
+This module contains predicates that are only available in
+the WASM (WebAssembly) version of Scryer Prolog.
+*/
+
+:- module(wasm, [js_eval/2]).
+
+:- use_module(library(error)).
+
+%% js_eval(+JsCode, -Result).
+%
+% Executes a JavaScript snippet `JsCode` using the platform
+% `eval` function. `Result` takes the return value of that code.
+% Strings, booleans, numbers, null and undefined are directly mapped to Prolog.
+% Arrays, objects, bigints, symbols and functions are not mapped.
+% Instead, a `js_{type}` atom will be returned.
+%
+% Example (on a browser):
+%
+% ```
+% ?- js_eval("prompt('What is your name?')", Name).
+%    % A prompt is showed, with a textbox.
+%    Name = "Whatever was written on the textbox".
+% ```
+js_eval(JsCode, Result) :-
+    must_be(chars, JsCode),
+    can_be(chars, Result),
+    '$js_eval'(JsCode, Result).