feat(eval): implements basic eval filtering

1 files changed, 24 insertions, 0 deletions

diff --git a/src/eval/index.ts b/src/eval/index.ts
new file mode 100644
index 0000000..e88b583
--- /dev/null
+++ b/src/eval/index.ts
@@ -0,0 +1,24 @@
+import {pipe} from 'fp-ts/function';
+import { Expr, ListExpr } from '../types'
+import {match} from '../utils';
+
+export const find = <T>([startO, exprs, endO]: ListExpr, list: T[]): any => {
+  const check = (e: Expr) => <T>(x: T, _i: number, _l: T[]): boolean => {
+    return pipe(
+      e.tag as any,
+      match({
+        AnyItem: () => true,
+        AnyNumber: () => typeof x === 'number',
+        AnyString: () => typeof x === 'string',
+        AnyBool: () => typeof x === 'boolean',
+        Truthy: () => !!x,
+        Falsey: () => !x,
+        _: () => false,
+      })
+    )
+  };
+  
+  const cs = exprs.map(check)
+
+  return list.filter((x, i, ls) => cs.every(c => c(x, i, ls)))
+}