Merge pull request #5929 from roc-lang/list-appendif

Add List.appendIfOk and List.prependIfOk
roc-lang · Nov 6, 2023 · 0252a11 · 0252a11
2 parents f0e3d65 + abff41c
commit 0252a11
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diff --git a/crates/compiler/builtins/roc/List.roc b/crates/compiler/builtins/roc/List.roc
@@ -6,6 +6,9 @@ interface List
         replace,
         update,
         append,
+        appendIfOk,
+        prepend,
+        prependIfOk,
         map,
         len,
         withCapacity,
@@ -15,7 +18,6 @@ interface List
         single,
         repeat,
         reverse,
-        prepend,
         join,
         keepIf,
         contains,
@@ -320,6 +322,21 @@ append = \list, element ->
     |> List.reserve 1
     |> List.appendUnsafe element
 
+## If the given [Result] is `Ok`, add it to the end of a list.
+## Otherwise, return the list unmodified.
+##
+## ```
+## List.appendIfOk [1, 2, 3] (Ok 4)
+##
+## [0, 1, 2]
+##     |> List.appendIfOk (Err 3)
+## ```
+appendIfOk : List a, Result a * -> List a
+appendIfOk = \list, result ->
+    when result is
+        Ok elem -> append list elem
+        Err _ -> list
+
 ## Writes the element after the current last element unconditionally.
 ## In other words, it is assumed that
 ##
@@ -336,6 +353,21 @@ appendUnsafe : List a, a -> List a
 ## ```
 prepend : List a, a -> List a
 
+## If the given [Result] is `Ok`, add it to the beginning of a list.
+## Otherwise, return the list unmodified.
+##
+## ```
+## List.prepend [1, 2, 3] (Ok 0)
+##
+## [2, 3, 4]
+##     |> List.prepend (Err 1)
+## ```
+prependIfOk : List a, Result a * -> List a
+prependIfOk = \list, result ->
+    when result is
+        Ok elem -> prepend list elem
+        Err _ -> list
+
 ## Returns the length of the list - the number of elements it contains.
 ##
 ## One [List] can store up to 2,147,483,648 elements (just over 2 billion), which

diff --git a/crates/compiler/gen_dev/src/lib.rs b/crates/compiler/gen_dev/src/lib.rs
@@ -1941,7 +1941,12 @@ trait Backend<'a> {
                 self.build_eq(sym, &args[0], &Symbol::DEV_TMP, &arg_layouts[0]);
                 self.free_symbol(&Symbol::DEV_TMP)
             }
-            Symbol::LIST_GET | Symbol::LIST_SET | Symbol::LIST_REPLACE | Symbol::LIST_APPEND => {
+            Symbol::LIST_GET
+            | Symbol::LIST_SET
+            | Symbol::LIST_REPLACE
+            | Symbol::LIST_APPEND
+            | Symbol::LIST_APPEND_IF_OK
+            | Symbol::LIST_PREPEND_IF_OK => {
                 // TODO: This is probably simple enough to be worth inlining.
                 let fn_name = self.lambda_name_to_string(
                     func_name,

diff --git a/crates/compiler/module/src/symbol.rs b/crates/compiler/module/src/symbol.rs
@@ -1433,6 +1433,8 @@ define_builtins! {
         81 LIST_RELEASE_EXCESS_CAPACITY: "releaseExcessCapacity"
         82 LIST_UPDATE: "update"
         83 LIST_WALK_WITH_INDEX: "walkWithIndex"
+        84 LIST_APPEND_IF_OK: "appendIfOk"
+        85 LIST_PREPEND_IF_OK: "prependIfOk"
     }
     7 RESULT: "Result" => {
         0 RESULT_RESULT: "Result" exposed_type=true // the Result.Result type alias

diff --git a/...s/compiler/test_mono/generated/anonymous_closure_in_polymorphic_expression_issue_4717.txt b/...s/compiler/test_mono/generated/anonymous_closure_in_polymorphic_expression_issue_4717.txt
@@ -2,88 +2,88 @@ procedure Bool.11 (#Attr.2, #Attr.3):
     let Bool.24 : Int1 = lowlevel Eq #Attr.2 #Attr.3;
     ret Bool.24;
 
-procedure List.26 (List.173, List.174, List.175):
-    let List.560 : [C U64, C U64] = CallByName List.97 List.173 List.174 List.175;
-    let List.563 : U8 = 1i64;
-    let List.564 : U8 = GetTagId List.560;
-    let List.565 : Int1 = lowlevel Eq List.563 List.564;
-    if List.565 then
-        let List.176 : U64 = UnionAtIndex (Id 1) (Index 0) List.560;
-        ret List.176;
+procedure List.26 (List.181, List.182, List.183):
+    let List.568 : [C U64, C U64] = CallByName List.99 List.181 List.182 List.183;
+    let List.571 : U8 = 1i64;
+    let List.572 : U8 = GetTagId List.568;
+    let List.573 : Int1 = lowlevel Eq List.571 List.572;
+    if List.573 then
+        let List.184 : U64 = UnionAtIndex (Id 1) (Index 0) List.568;
+        ret List.184;
     else
-        let List.177 : U64 = UnionAtIndex (Id 0) (Index 0) List.560;
-        ret List.177;
+        let List.185 : U64 = UnionAtIndex (Id 0) (Index 0) List.568;
+        ret List.185;
 
-procedure List.38 (List.316, List.317):
-    let List.559 : U64 = CallByName List.6 List.316;
-    let List.318 : U64 = CallByName Num.77 List.559 List.317;
-    let List.545 : List U8 = CallByName List.43 List.316 List.318;
-    ret List.545;
+procedure List.38 (List.324, List.325):
+    let List.567 : U64 = CallByName List.6 List.324;
+    let List.326 : U64 = CallByName Num.77 List.567 List.325;
+    let List.553 : List U8 = CallByName List.43 List.324 List.326;
+    ret List.553;
 
-procedure List.43 (List.314, List.315):
-    let List.557 : U64 = CallByName List.6 List.314;
-    let List.556 : U64 = CallByName Num.77 List.557 List.315;
-    let List.547 : {U64, U64} = Struct {List.315, List.556};
-    let List.546 : List U8 = CallByName List.49 List.314 List.547;
-    ret List.546;
+procedure List.43 (List.322, List.323):
+    let List.565 : U64 = CallByName List.6 List.322;
+    let List.564 : U64 = CallByName Num.77 List.565 List.323;
+    let List.555 : {U64, U64} = Struct {List.323, List.564};
+    let List.554 : List U8 = CallByName List.49 List.322 List.555;
+    ret List.554;
 
-procedure List.49 (List.392, List.393):
-    let List.554 : U64 = StructAtIndex 0 List.393;
-    let List.555 : U64 = 0i64;
-    let List.552 : Int1 = CallByName Bool.11 List.554 List.555;
-    if List.552 then
-        dec List.392;
-        let List.553 : List U8 = Array [];
-        ret List.553;
+procedure List.49 (List.400, List.401):
+    let List.562 : U64 = StructAtIndex 0 List.401;
+    let List.563 : U64 = 0i64;
+    let List.560 : Int1 = CallByName Bool.11 List.562 List.563;
+    if List.560 then
+        dec List.400;
+        let List.561 : List U8 = Array [];
+        ret List.561;
     else
-        let List.549 : U64 = StructAtIndex 1 List.393;
-        let List.550 : U64 = StructAtIndex 0 List.393;
-        let List.548 : List U8 = CallByName List.72 List.392 List.549 List.550;
-        ret List.548;
+        let List.557 : U64 = StructAtIndex 1 List.401;
+        let List.558 : U64 = StructAtIndex 0 List.401;
+        let List.556 : List U8 = CallByName List.72 List.400 List.557 List.558;
+        ret List.556;
 
 procedure List.6 (#Attr.2):
-    let List.558 : U64 = lowlevel ListLen #Attr.2;
-    ret List.558;
+    let List.566 : U64 = lowlevel ListLen #Attr.2;
+    ret List.566;
 
 procedure List.66 (#Attr.2, #Attr.3):
-    let List.581 : U8 = lowlevel ListGetUnsafe #Attr.2 #Attr.3;
-    ret List.581;
+    let List.589 : U8 = lowlevel ListGetUnsafe #Attr.2 #Attr.3;
+    ret List.589;
 
 procedure List.72 (#Attr.2, #Attr.3, #Attr.4):
-    let List.551 : List U8 = lowlevel ListSublist #Attr.2 #Attr.3 #Attr.4;
-    ret List.551;
+    let List.559 : List U8 = lowlevel ListSublist #Attr.2 #Attr.3 #Attr.4;
+    ret List.559;
 
 procedure List.80 (#Derived_gen.0, #Derived_gen.1, #Derived_gen.2, #Derived_gen.3, #Derived_gen.4):
-    joinpoint List.569 List.463 List.464 List.465 List.466 List.467:
-        let List.571 : Int1 = CallByName Num.22 List.466 List.467;
-        if List.571 then
-            let List.580 : U8 = CallByName List.66 List.463 List.466;
-            let List.572 : [C U64, C U64] = CallByName Test.4 List.464 List.580;
-            let List.577 : U8 = 1i64;
-            let List.578 : U8 = GetTagId List.572;
-            let List.579 : Int1 = lowlevel Eq List.577 List.578;
-            if List.579 then
-                let List.468 : U64 = UnionAtIndex (Id 1) (Index 0) List.572;
-                let List.575 : U64 = 1i64;
-                let List.574 : U64 = CallByName Num.51 List.466 List.575;
-                jump List.569 List.463 List.468 List.465 List.574 List.467;
+    joinpoint List.577 List.471 List.472 List.473 List.474 List.475:
+        let List.579 : Int1 = CallByName Num.22 List.474 List.475;
+        if List.579 then
+            let List.588 : U8 = CallByName List.66 List.471 List.474;
+            let List.580 : [C U64, C U64] = CallByName Test.4 List.472 List.588;
+            let List.585 : U8 = 1i64;
+            let List.586 : U8 = GetTagId List.580;
+            let List.587 : Int1 = lowlevel Eq List.585 List.586;
+            if List.587 then
+                let List.476 : U64 = UnionAtIndex (Id 1) (Index 0) List.580;
+                let List.583 : U64 = 1i64;
+                let List.582 : U64 = CallByName Num.51 List.474 List.583;
+                jump List.577 List.471 List.476 List.473 List.582 List.475;
             else
-                dec List.463;
-                let List.469 : U64 = UnionAtIndex (Id 0) (Index 0) List.572;
-                let List.576 : [C U64, C U64] = TagId(0) List.469;
-                ret List.576;
+                dec List.471;
+                let List.477 : U64 = UnionAtIndex (Id 0) (Index 0) List.580;
+                let List.584 : [C U64, C U64] = TagId(0) List.477;
+                ret List.584;
         else
-            dec List.463;
-            let List.570 : [C U64, C U64] = TagId(1) List.464;
-            ret List.570;
+            dec List.471;
+            let List.578 : [C U64, C U64] = TagId(1) List.472;
+            ret List.578;
     in
-    jump List.569 #Derived_gen.0 #Derived_gen.1 #Derived_gen.2 #Derived_gen.3 #Derived_gen.4;
+    jump List.577 #Derived_gen.0 #Derived_gen.1 #Derived_gen.2 #Derived_gen.3 #Derived_gen.4;
 
-procedure List.97 (List.460, List.461, List.462):
-    let List.567 : U64 = 0i64;
-    let List.568 : U64 = CallByName List.6 List.460;
-    let List.566 : [C U64, C U64] = CallByName List.80 List.460 List.461 List.462 List.567 List.568;
-    ret List.566;
+procedure List.99 (List.468, List.469, List.470):
+    let List.575 : U64 = 0i64;
+    let List.576 : U64 = CallByName List.6 List.468;
+    let List.574 : [C U64, C U64] = CallByName List.80 List.468 List.469 List.470 List.575 List.576;
+    ret List.574;
 
 procedure Num.22 (#Attr.2, #Attr.3):
     let Num.294 : Int1 = lowlevel NumLt #Attr.2 #Attr.3;

diff --git a/crates/compiler/test_mono/generated/call_function_in_empty_list.txt b/crates/compiler/test_mono/generated/call_function_in_empty_list.txt
@@ -1,7 +1,7 @@
 procedure List.5 (#Attr.2, #Attr.3):
-    let List.545 : List {} = lowlevel ListMap { xs: `#Attr.#arg1` } #Attr.2 Test.2 #Attr.3;
+    let List.553 : List {} = lowlevel ListMap { xs: `#Attr.#arg1` } #Attr.2 Test.2 #Attr.3;
     decref #Attr.2;
-    ret List.545;
+    ret List.553;
 
 procedure Test.2 (Test.3):
     let Test.7 : {} = Struct {};

diff --git a/crates/compiler/test_mono/generated/call_function_in_empty_list_unbound.txt b/crates/compiler/test_mono/generated/call_function_in_empty_list_unbound.txt
@@ -1,7 +1,7 @@
 procedure List.5 (#Attr.2, #Attr.3):
-    let List.545 : List [] = lowlevel ListMap { xs: `#Attr.#arg1` } #Attr.2 Test.2 #Attr.3;
+    let List.553 : List [] = lowlevel ListMap { xs: `#Attr.#arg1` } #Attr.2 Test.2 #Attr.3;
     decref #Attr.2;
-    ret List.545;
+    ret List.553;
 
 procedure Test.2 (Test.3):
     let Test.7 : {} = Struct {};

diff --git a/crates/compiler/test_mono/generated/capture_void_layout_task.txt b/crates/compiler/test_mono/generated/capture_void_layout_task.txt
@@ -1,31 +1,31 @@
-procedure List.18 (List.146, List.147, List.148):
-    let List.546 : U64 = 0i64;
-    let List.547 : U64 = CallByName List.6 List.146;
-    let List.545 : [<r>C {}, C *self {{}, []}] = CallByName List.86 List.146 List.147 List.148 List.546 List.547;
-    ret List.545;
+procedure List.18 (List.154, List.155, List.156):
+    let List.554 : U64 = 0i64;
+    let List.555 : U64 = CallByName List.6 List.154;
+    let List.553 : [<r>C {}, C *self {{}, []}] = CallByName List.88 List.154 List.155 List.156 List.554 List.555;
+    ret List.553;
 
 procedure List.6 (#Attr.2):
-    let List.556 : U64 = lowlevel ListLen #Attr.2;
-    ret List.556;
+    let List.564 : U64 = lowlevel ListLen #Attr.2;
+    ret List.564;
 
 procedure List.66 (#Attr.2, #Attr.3):
-    let List.555 : [] = lowlevel ListGetUnsafe #Attr.2 #Attr.3;
-    ret List.555;
-
-procedure List.86 (#Derived_gen.13, #Derived_gen.14, #Derived_gen.15, #Derived_gen.16, #Derived_gen.17):
-    joinpoint List.548 List.149 List.150 List.151 List.152 List.153:
-        let List.550 : Int1 = CallByName Num.22 List.152 List.153;
-        if List.550 then
-            let List.554 : [] = CallByName List.66 List.149 List.152;
-            let List.154 : [<r>C {}, C *self {{}, []}] = CallByName Test.29 List.150 List.554 List.151;
-            let List.553 : U64 = 1i64;
-            let List.552 : U64 = CallByName Num.51 List.152 List.553;
-            jump List.548 List.149 List.154 List.151 List.552 List.153;
+    let List.563 : [] = lowlevel ListGetUnsafe #Attr.2 #Attr.3;
+    ret List.563;
+
+procedure List.88 (#Derived_gen.3, #Derived_gen.4, #Derived_gen.5, #Derived_gen.6, #Derived_gen.7):
+    joinpoint List.556 List.157 List.158 List.159 List.160 List.161:
+        let List.558 : Int1 = CallByName Num.22 List.160 List.161;
+        if List.558 then
+            let List.562 : [] = CallByName List.66 List.157 List.160;
+            let List.162 : [<r>C {}, C *self {{}, []}] = CallByName Test.29 List.158 List.562 List.159;
+            let List.561 : U64 = 1i64;
+            let List.560 : U64 = CallByName Num.51 List.160 List.561;
+            jump List.556 List.157 List.162 List.159 List.560 List.161;
         else
-            dec List.149;
-            ret List.150;
+            dec List.157;
+            ret List.158;
     in
-    jump List.548 #Derived_gen.13 #Derived_gen.14 #Derived_gen.15 #Derived_gen.16 #Derived_gen.17;
+    jump List.556 #Derived_gen.3 #Derived_gen.4 #Derived_gen.5 #Derived_gen.6 #Derived_gen.7;
 
 procedure Num.22 (#Attr.2, #Attr.3):
     let Num.292 : Int1 = lowlevel NumLt #Attr.2 #Attr.3;

diff --git a/crates/compiler/test_mono/generated/choose_correct_recursion_var_under_record.txt b/crates/compiler/test_mono/generated/choose_correct_recursion_var_under_record.txt
@@ -2,49 +2,49 @@ procedure Bool.1 ():
     let Bool.24 : Int1 = false;
     ret Bool.24;
 
-procedure List.2 (List.101, List.102):
-    let List.559 : U64 = CallByName List.6 List.101;
-    let List.555 : Int1 = CallByName Num.22 List.102 List.559;
-    if List.555 then
-        let List.557 : Str = CallByName List.66 List.101 List.102;
-        inc List.557;
-        dec List.101;
-        let List.556 : [C {}, C Str] = TagId(1) List.557;
-        ret List.556;
+procedure List.2 (List.103, List.104):
+    let List.567 : U64 = CallByName List.6 List.103;
+    let List.563 : Int1 = CallByName Num.22 List.104 List.567;
+    if List.563 then
+        let List.565 : Str = CallByName List.66 List.103 List.104;
+        inc List.565;
+        dec List.103;
+        let List.564 : [C {}, C Str] = TagId(1) List.565;
+        ret List.564;
     else
-        dec List.101;
-        let List.554 : {} = Struct {};
-        let List.553 : [C {}, C Str] = TagId(0) List.554;
-        ret List.553;
+        dec List.103;
+        let List.562 : {} = Struct {};
+        let List.561 : [C {}, C Str] = TagId(0) List.562;
+        ret List.561;
 
 procedure List.5 (#Attr.2, #Attr.3):
-    let List.561 : List Str = lowlevel ListMap { xs: `#Attr.#arg1` } #Attr.2 Test.10 #Attr.3;
+    let List.569 : List Str = lowlevel ListMap { xs: `#Attr.#arg1` } #Attr.2 Test.10 #Attr.3;
     decref #Attr.2;
-    ret List.561;
+    ret List.569;
 
 procedure List.6 (#Attr.2):
-    let List.560 : U64 = lowlevel ListLen #Attr.2;
-    ret List.560;
+    let List.568 : U64 = lowlevel ListLen #Attr.2;
+    ret List.568;
 
 procedure List.66 (#Attr.2, #Attr.3):
-    let List.558 : Str = lowlevel ListGetUnsafe #Attr.2 #Attr.3;
-    ret List.558;
+    let List.566 : Str = lowlevel ListGetUnsafe #Attr.2 #Attr.3;
+    ret List.566;
 
-procedure List.9 (List.307):
-    let List.552 : U64 = 0i64;
-    let List.545 : [C {}, C Str] = CallByName List.2 List.307 List.552;
-    let List.549 : U8 = 1i64;
-    let List.550 : U8 = GetTagId List.545;
-    let List.551 : Int1 = lowlevel Eq List.549 List.550;
-    if List.551 then
-        let List.308 : Str = UnionAtIndex (Id 1) (Index 0) List.545;
-        let List.546 : [C {}, C Str] = TagId(1) List.308;
-        ret List.546;
+procedure List.9 (List.315):
+    let List.560 : U64 = 0i64;
+    let List.553 : [C {}, C Str] = CallByName List.2 List.315 List.560;
+    let List.557 : U8 = 1i64;
+    let List.558 : U8 = GetTagId List.553;
+    let List.559 : Int1 = lowlevel Eq List.557 List.558;
+    if List.559 then
+        let List.316 : Str = UnionAtIndex (Id 1) (Index 0) List.553;
+        let List.554 : [C {}, C Str] = TagId(1) List.316;
+        ret List.554;
     else
-        dec List.545;
-        let List.548 : {} = Struct {};
-        let List.547 : [C {}, C Str] = TagId(0) List.548;
-        ret List.547;
+        dec List.553;
+        let List.556 : {} = Struct {};
+        let List.555 : [C {}, C Str] = TagId(0) List.556;
+        ret List.555;
 
 procedure Num.22 (#Attr.2, #Attr.3):
     let Num.291 : Int1 = lowlevel NumLt #Attr.2 #Attr.3;