feat(literal): add support for 'true', 'false', 'null' literals

src/lang/literals/keywords.fnk

@@ -0,0 +1,8 @@
+{booleanLiteral, nullLiteral} = import '@babel/types'
+
+
+transform_keyword = fn node:
+  match node:
+    {'value': 'true'}: booleanLiteral:: true
+    {'value': 'false'}: booleanLiteral:: false
+    {'value': 'null'}: nullLiteral()

src/lang/literals/keywords.test.fnk

@@ -0,0 +1,13 @@
+{fink2js} = import '../../testing'
+{describe, it, expect, to_match_snapshot} = import '@fink/jest'
+
+
+describe:: 'keywords', fn:
+  it:: 'transforms literals', fn:
+    expect::
+      fink2js`
+        x = false
+        y = true
+        z = null
+      `
+      to_match_snapshot

src/lang/literals/keywords.test.fnk.snap

@@ -0,0 +1,12 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`keywords transforms literals 1`] = `
+"const x = false;
+const y = true;
+const z = null;
+Object.assign(module.exports, {
+  x,
+  y,
+  z
+});"
+`;