fix: handle __functor in forceFunction

nix-js/runtime-ts/src/builtins/derivation.ts

@@ -204,14 +204,32 @@ interface FixedOutputInfo {
   hashMode: string;
 }
 
-const extractFixedOutputInfo = (attrs: NixAttrs): FixedOutputInfo | null => {
+const extractFixedOutputInfo = (attrs: NixAttrs, ignoreNulls: boolean): FixedOutputInfo | null => {
   if (!("outputHash" in attrs)) {
     return null;
   }
 
+  const hashValue = force(attrs.outputHash);
+  if (ignoreNulls && hashValue === null) {
+    return null;
+  }
   const hash = forceStringValue(attrs.outputHash);
-  const hashAlgo = "outputHashAlgo" in attrs ? forceStringValue(attrs.outputHashAlgo) : "sha256";
-  const hashMode = "outputHashMode" in attrs ? forceStringValue(attrs.outputHashMode) : "flat";
+
+  let hashAlgo = "sha256";
+  if ("outputHashAlgo" in attrs) {
+    const algoValue = force(attrs.outputHashAlgo);
+    if (!(ignoreNulls && algoValue === null)) {
+      hashAlgo = forceStringValue(attrs.outputHashAlgo);
+    }
+  }
+
+  let hashMode = "flat";
+  if ("outputHashMode" in attrs) {
+    const modeValue = force(attrs.outputHashMode);
+    if (!(ignoreNulls && modeValue === null)) {
+      hashMode = forceStringValue(attrs.outputHashMode);
+    }
+  }
 
   if (hashMode !== "flat" && hashMode !== "recursive") {
     throw new Error(`derivation: invalid outputHashMode '${hashMode}' (must be 'flat' or 'recursive')`);
@@ -234,14 +252,13 @@ export const derivationStrict = (args: NixValue): NixAttrs => {
   const builder = validateBuilder(attrs, collectedContext);
   const platform = validateSystem(attrs);
 
-  const outputs = extractOutputs(attrs);
-  const fixedOutputInfo = extractFixedOutputInfo(attrs);
-  validateFixedOutputConstraints(fixedOutputInfo, outputs);
-
   const structuredAttrs = "__structuredAttrs" in attrs ? force(attrs.__structuredAttrs) === true : false;
-
   const ignoreNulls = "__ignoreNulls" in attrs ? force(attrs.__ignoreNulls) === true : false;
 
+  const outputs = extractOutputs(attrs);
+  const fixedOutputInfo = extractFixedOutputInfo(attrs, ignoreNulls);
+  validateFixedOutputConstraints(fixedOutputInfo, outputs);
+
   if ("__contentAddressed" in attrs && force(attrs.__contentAddressed) === true) {
     throw new Error("ca derivations are not supported");
   }

nix-js/runtime-ts/src/type-assert.ts

@@ -16,7 +16,6 @@ import type {
 } from "./types";
 import { isStringWithContext, isNixPath } from "./types";
 import { force } from "./thunk";
-import { getStringValue } from "./string-context";
 import { isAttrs, isFunction, typeOf } from "./builtins/type-check";
 
 /**
@@ -32,15 +31,25 @@ export const forceList = (value: NixValue): NixList => {
 };
 
 /**
- * Force a value and assert it's a function
- * @throws TypeError if value is not a function after forcing
+ * Force a value and assert it's a function or functor
+ * @throws TypeError if value is not a function or functor after forcing
  */
 export const forceFunction = (value: NixValue): NixFunction => {
   const forced = force(value);
-  if (!isFunction(forced)) {
-    throw new TypeError(`Expected function, got ${typeOf(forced)}`);
-  }
+  if (isFunction(forced)) {
     return forced;
+  }
+  if (
+    typeof forced === "object" &&
+    !Array.isArray(forced) &&
+    forced !== null &&
+    "__functor" in forced
+  ) {
+    const functorSet = forced as NixAttrs;
+    const functor = forceFunction(functorSet.__functor);
+    return (arg: NixValue) => forceFunction(functor(functorSet))(arg);
+  }
+  throw new TypeError(`Expected function, got ${typeOf(forced)}`);
 };
 
 /**

nix-js/src/codegen.rs

@@ -473,15 +473,14 @@ impl<Ctx: CodegenContext> Compile<Ctx> for [(ExprId, ExprId)] {
             let inner_ir = ctx.get_ir(inner);
             let inner_span = inner_ir.span();
 
-            code!(buf, "let expr{}=Nix.createThunk(()=>(", slot.0);
-            inner_ir.compile(ctx, buf);
             code!(
-                buf,
-                "),\"expr{} {}:{}:{}\");",
-                slot.0,
-                ctx.get_current_source().get_name(),
-                usize::from(inner_span.start()),
+                buf, ctx;
+                "let expr" slot.0 "=Nix.createThunk(()=>(" inner_ir "),"
+                "\"expr" slot.0 " "
+                ctx.get_current_source().get_name() ":"
+                usize::from(inner_span.start()) ":"
                 usize::from(inner_span.end())
+                "\");"
             );
         }
     }