Prettier

src/core.js

   '<': (a, b) => new AST.Boolean({ value: a.value < b.value }),
   '>=': (a, b) => new AST.Boolean({ value: a.value >= b.value }),
   '<=': (a, b) => new AST.Boolean({ value: a.value <= b.value }),
-  'list': (...args) => { return new AST.List({ elements: args }) },
-  'length': xs => new AST.Number({ value: xs.elements.length }),
-  'cons': (x, xs) => new AST.List({ elements: [x, ...xs.elements] }),
-  'head': xs => xs.elements[0],
-  'tail': xs => new AST.List({ elements: xs.elements.slice(1) }),
+  list: (...args) => {
+    return new AST.List({ elements: args })
+  },
+  length: xs => new AST.Number({ value: xs.elements.length }),
+  cons: (x, xs) => new AST.List({ elements: [x, ...xs.elements] }),
+  head: xs => xs.elements[0],
+  tail: xs => new AST.List({ elements: xs.elements.slice(1) }),
 }

test/coreTest.js

   t.plan(1)
 
   const tree = helpers.evaluate('(list 1 2 3)')
-  t.deepEqual(tree[0], new AST.List({
-    elements: [
-      new AST.Number({ value: 1, line: 1 }),
-      new AST.Number({ value: 2, line: 1 }),
-      new AST.Number({ value: 3, line: 1 }),
-    ]
-  }))
+  t.deepEqual(
+    tree[0],
+    new AST.List({
+      elements: [
+        new AST.Number({ value: 1, line: 1 }),
+        new AST.Number({ value: 2, line: 1 }),
+        new AST.Number({ value: 3, line: 1 }),
+      ],
+    }),
+  )
 })
 
 test('length function', t => {
 
     (my-map (lambda (x) (+ x 1)) (list 1 2 3))
   `)
-  t.deepEqual(tree[0], new AST.List({ elements: [
-    new AST.Number({ value: 2 }),
-    new AST.Number({ value: 3 }),
-    new AST.Number({ value: 4 }),
-  ]}))
+  t.deepEqual(
+    tree[0],
+    new AST.List({
+      elements: [
+        new AST.Number({ value: 2 }),
+        new AST.Number({ value: 3 }),
+        new AST.Number({ value: 4 }),
+      ],
+    }),
+  )
 })