diff --git a/slige/compiler/check/checker.ts b/slige/compiler/check/checker.ts
index 3edb111..d31b518 100644
--- a/slige/compiler/check/checker.ts
+++ b/slige/compiler/check/checker.ts
@@ -26,7 +26,7 @@ export class Checker {
     public constructor(
         private ctx: Ctx,
         private entryFileAst: ast.File,
-        private resols: resolve.Resols,
+        private re: resolve.Resols,
     ) {
         this.currentFile = ctx.entryFile();
     }
@@ -48,20 +48,20 @@ export class Checker {
 
         const exprTy = kind.expr && Ok(this.exprTy(kind.expr));
         const tyTy = kind.ty && Ok(this.tyTy(kind.ty));
-        const ty = exprTy !== undefined
-            ? tyTy !== undefined
-                ? this.resolveTys(exprTy.val, tyTy.val)
-                : exprTy
-            : exprTy;
+        const ty = exprTy !== undefined && tyTy !== undefined
+            ? this.resolveTys(exprTy.val, tyTy.val)
+            : exprTy || tyTy;
 
         this.stmtChecked.add(stmt.id);
 
         if (ty === undefined) {
+            this.assignPatTy(kind.pat, Ty({ tag: "error" }));
             this.report("type amfibious, specify type or value", stmt.span);
             return Ty({ tag: "error" });
         }
 
         if (!ty.ok) {
+            this.assignPatTy(kind.pat, Ty({ tag: "error" }));
             this.report(ty.val, stmt.span);
             return Ty({ tag: "error" });
         }
@@ -116,7 +116,7 @@ export class Checker {
             case "int":
                 return Ty({ tag: "int" });
             case "bool":
-                return todo();
+                return Ty({ tag: "bool" });
             case "str":
                 return todo();
             case "group":
@@ -141,12 +141,58 @@ export class Checker {
                 return this.checkCallExpr(expr, k, expected);
             case "unary":
                 return todo();
-            case "binary":
-                return todo();
-            case "block":
-                return todo();
-            case "if":
-                return todo();
+            case "binary": {
+                const res = this.resolveTys(
+                    this.exprTy(k.left),
+                    this.exprTy(k.right),
+                );
+                if (!res.ok) {
+                    this.exprTys.set(expr.id, Ty({ tag: "error" }));
+                    this.report(res.val, expr.span);
+                    return Ty({ tag: "error" });
+                }
+                this.exprTys.set(expr.id, res.val);
+                return res.val;
+            }
+            case "block": {
+                const ty = this.checkBlock(k.block, expected);
+                return ty;
+            }
+            case "if": {
+                const cond = this.exprTy(k.cond);
+                const condRes = this.resolveTys(cond, Ty({ tag: "bool" }));
+                if (!condRes.ok) {
+                    this.exprTys.set(expr.id, Ty({ tag: "error" }));
+                    this.report("if-condition must be a boolean", k.cond.span);
+                    return Ty({ tag: "error" });
+                }
+                const truthy = this.exprTy(k.truthy);
+                if (!k.falsy) {
+                    const truthyRes = this.resolveTys(
+                        truthy,
+                        Ty({ tag: "null" }),
+                    );
+                    if (!truthyRes.ok) {
+                        this.exprTys.set(expr.id, Ty({ tag: "error" }));
+                        this.report(
+                            "if there isn't a falsy-clause, then the truthy clause must evaluate to null",
+                            k.truthy.span,
+                        );
+                        return Ty({ tag: "error" });
+                    }
+                    this.exprTys.set(expr.id, Ty({ tag: "null" }));
+                    return Ty({ tag: "null" });
+                }
+                const falsy = this.exprTy(k.falsy);
+                const bothRes = this.resolveTys(truthy, falsy);
+                if (!bothRes.ok) {
+                    this.exprTys.set(expr.id, Ty({ tag: "error" }));
+                    this.report(bothRes.val, k.truthy.span);
+                    return Ty({ tag: "error" });
+                }
+                this.exprTys.set(expr.id, bothRes.val);
+                return bothRes.val;
+            }
             case "loop":
                 return todo();
             case "while":
@@ -164,7 +210,7 @@ export class Checker {
         kind: ast.PathExpr,
         expected: Ty,
     ): Ty {
-        const res = this.resols.exprRes(expr.id);
+        const res = this.re.exprRes(expr.id);
         switch (res.kind.tag) {
             case "error":
                 return Ty({ tag: "error" });
@@ -179,7 +225,7 @@ export class Checker {
                 return resu.val;
             }
             case "local": {
-                const patRes = this.resols.patRes(res.kind.id);
+                const patRes = this.re.patRes(res.kind.id);
                 const ty = this.patTy(patRes.pat);
                 const resu = this.resolveTys(ty, expected);
                 if (!resu.ok) {
@@ -256,7 +302,7 @@ export class Checker {
     }
 
     private checkPat(pat: ast.Pat): Ty {
-        const patRes = this.resols.patRes(pat.id);
+        const patRes = this.re.patRes(pat.id);
         const k = pat.kind;
         switch (k.tag) {
             case "error":
@@ -303,12 +349,13 @@ export class Checker {
         if (b.kind.tag === "unknown") {
             return Res.Ok(a);
         }
-        const as = tyToString(this.ctx, a);
-        const bs = tyToString(this.ctx, b);
-        const incompat = () =>
-            Res.Err(
+        const incompat = () => {
+            const as = tyToString(this.ctx, a);
+            const bs = tyToString(this.ctx, b);
+            return Res.Err(
                 `type '${as}' not compatible with type '${bs}'`,
             );
+        };
         switch (a.kind.tag) {
             case "unknown":
                 return this.resolveTys(b, a);
@@ -324,6 +371,12 @@ export class Checker {
                 }
                 return Res.Ok(a);
             }
+            case "bool": {
+                if (b.kind.tag !== "bool") {
+                    return incompat();
+                }
+                return Res.Ok(a);
+            }
             case "fn": {
                 if (b.kind.tag !== "fn") {
                     return incompat();
diff --git a/slige/compiler/middle/ast_lower.ts b/slige/compiler/middle/ast_lower.ts
index 6a6c44f..669f150 100644
--- a/slige/compiler/middle/ast_lower.ts
+++ b/slige/compiler/middle/ast_lower.ts
@@ -3,15 +3,8 @@ import { Checker } from "@slige/check";
 import { AstId, Ctx, exhausted, IdMap, Ids, Res, todo } from "@slige/common";
 import { Resols } from "@slige/resolve";
 import { Ty } from "@slige/ty";
-import {
-    BinaryType,
-    Operand,
-    Place,
-    ProjElem,
-    StmtKind,
-    TerKind,
-} from "./mir.ts";
-import { Block, BlockId, Fn, Local, LocalId, RVal, Stmt, Ter } from "./mir.ts";
+import { BinaryType, Operand, ProjElem, StmtKind, TerKind } from "./mir.ts";
+import { Block, BlockId, Fn, Local, LocalId, RVal } from "./mir.ts";
 import { MirFnStringifyer } from "@slige/stringify";
 
 export class AstLowerer implements ast.Visitor {
@@ -55,6 +48,8 @@ export class FnLowerer {
 
     private reLocals = new IdMap<AstId, LocalId>();
 
+    private paramLocals = new IdMap<LocalId, number>();
+
     public constructor(
         private ctx: Ctx,
         private re: Resols,
@@ -85,7 +80,10 @@ export class FnLowerer {
             label: this.ctx.identText(this.item.ident.id),
             locals: this.locals,
             blocks: this.blocks,
-            entry,
+            entry: entry.id,
+            paramLocals: this.paramLocals,
+            astItem: this.item,
+            astItemKind: this.kind,
         });
     }
 
@@ -112,8 +110,13 @@ export class FnLowerer {
             case "break":
             case "continue":
             case "assign":
-            case "expr":
                 return todo(k.tag);
+            case "expr": {
+                const rval = this.lowerExpr(k.expr);
+                // ignore the fuck out of the value
+                void rval;
+                return;
+            }
         }
         exhausted(k);
     }
@@ -122,13 +125,7 @@ export class FnLowerer {
         const val = kind.expr && this.lowerExpr(kind.expr);
         this.allocatePat(kind.pat);
         if (val) {
-            const local = this.local(this.ch.patTy(kind.pat));
-            this.addStmt({
-                tag: "assign",
-                place: { local: local, proj: [] },
-                rval: val,
-            });
-            this.assignPat(kind.pat, local, []);
+            this.assignPatRVal(kind.pat, val);
         }
     }
 
@@ -139,7 +136,7 @@ export class FnLowerer {
                 return;
             case "bind": {
                 const ty = this.ch.patTy(pat);
-                const local = this.local(ty);
+                const local = this.local(ty, k.ident);
                 this.reLocals.set(pat.id, local);
                 return;
             }
@@ -149,7 +146,27 @@ export class FnLowerer {
         exhausted(k);
     }
 
-    private assignPat(pat: ast.Pat, local: LocalId, proj: ProjElem[]) {
+    private assignPatRVal(pat: ast.Pat, rval: RVal) {
+        const k = pat.kind;
+        switch (k.tag) {
+            case "error":
+                return;
+            case "bind": {
+                const patLocal = this.reLocals.get(pat.id)!;
+                this.addStmt({
+                    tag: "assign",
+                    place: { local: patLocal, proj: [] },
+                    rval,
+                });
+                return;
+            }
+            case "path":
+                return todo();
+        }
+        exhausted(k);
+    }
+
+    private assignPat(pat: ast.Pat, local: LocalId, proj: ProjElem[] = []) {
         const k = pat.kind;
         switch (k.tag) {
             case "error":
@@ -180,19 +197,12 @@ export class FnLowerer {
             case "path":
                 return this.lowerPathExpr(expr, k);
             case "null":
-                return {
-                    tag: "use",
-                    operand: { tag: "const", val: { tag: "null" } },
-                };
             case "int":
+            case "bool":
                 return {
                     tag: "use",
-                    operand: {
-                        tag: "const",
-                        val: { tag: "int", value: k.value },
-                    },
+                    operand: this.lowerExprToOperand(expr),
                 };
-            case "bool":
             case "str":
             case "group":
             case "array":
@@ -211,7 +221,9 @@ export class FnLowerer {
             case "binary":
                 return this.lowerBinaryExpr(expr, k);
             case "block":
+                return this.lowerBlock(k.block);
             case "if":
+                return this.lowerIfExpr(expr, k);
             case "loop":
             case "while":
             case "for":
@@ -226,63 +238,25 @@ export class FnLowerer {
         switch (re.kind.tag) {
             case "error":
                 return { tag: "error" };
-            case "fn": {
-                const ty = this.ch.fnItemTy(re.kind.item, re.kind.kind);
-                const local = this.local(ty);
+            case "fn":
+            case "local":
                 return {
                     tag: "use",
-                    operand: { tag: "move", place: { local, proj: [] } },
+                    operand: this.lowerPathExprToOperand(expr, kind),
                 };
-            }
-            case "local": {
-                const ty = this.ch.exprTy(expr);
-                const local = this.local(ty);
-                this.reLocals.set(re.kind.id, local);
-                const isCopyable = (() => {
-                    switch (ty.kind.tag) {
-                        case "error":
-                        case "unknown":
-                            return false;
-                        case "null":
-                        case "int":
-                            return true;
-                        case "fn":
-                            return false;
-                    }
-                    exhausted(ty.kind);
-                })();
-                return {
-                    tag: "use",
-                    operand: {
-                        tag: isCopyable ? "copy" : "move",
-                        place: { local, proj: [] },
-                    },
-                };
-            }
         }
         exhausted(re.kind);
     }
 
     private lowerCallExpr(expr: ast.Expr, kind: ast.CallExpr): RVal {
-        const args = kind.args.map((arg) =>
-            this.rvalAsOperand(this.lowerExpr(arg), this.ch.exprTy(arg))
-        );
-        const func = this.rvalAsOperand(
-            this.lowerExpr(kind.expr),
-            this.ch.exprTy(expr),
-        );
+        const args = kind.args.map((arg) => this.lowerExprToOperand(arg));
+        const func = this.lowerExprToOperand(kind.expr);
         return { tag: "call", func, args };
     }
 
     private lowerBinaryExpr(expr: ast.Expr, kind: ast.BinaryExpr): RVal {
-        const left = this.rvalAsOperand(
-            this.lowerExpr(kind.left),
-            this.ch.exprTy(kind.left),
-        );
-        const right = this.rvalAsOperand(
-            this.lowerExpr(kind.right),
-            this.ch.exprTy(kind.right),
-        );
+        const left = this.lowerExprToOperand(kind.left);
+        const right = this.lowerExprToOperand(kind.right);
         const binaryType = ((kind): BinaryType => {
             switch (kind.binaryType) {
                 case "+":
@@ -315,19 +289,139 @@ export class FnLowerer {
         return { tag: "binary", binaryType, left, right };
     }
 
-    private rvalAsOperand(rval: RVal, ty: Ty): Operand {
-        const local = this.local(ty);
-        this.addStmt({ tag: "assign", place: { local, proj: [] }, rval });
-        return { tag: "move", place: { local, proj: [] } };
+    private lowerIfExpr(expr: ast.Expr, kind: ast.IfExpr): RVal {
+        const cond = this.lowerExprToOperand(kind.cond);
+        const condBlock = this.currentBlock!;
+        if (kind.falsy) {
+            return todo();
+        } else {
+            if (this.ch.exprTy(expr).kind.tag !== "null") {
+                throw new Error();
+            }
+            const truthBlock = this.pushBlock();
+            this.lowerExpr(kind.truthy);
+            const exit = this.pushBlock();
+            this.setTer({ tag: "goto", target: exit.id }, truthBlock);
+            this.setTer({
+                tag: "switch",
+                discr: cond,
+                targets: [{ value: 1, target: truthBlock.id }],
+                otherwise: exit.id,
+            }, condBlock);
+            return {
+                tag: "use",
+                operand: { tag: "const", val: { tag: "null" } },
+            };
+        }
     }
 
-    private local(ty: Ty): LocalId {
+    private lowerExprToOperand(expr: ast.Expr): Operand {
+        const k = expr.kind;
+        switch (k.tag) {
+            case "error":
+                return { tag: "error" };
+            case "path":
+                return this.lowerPathExprToOperand(expr, k);
+            case "null":
+                return { tag: "const", val: { tag: "null" } };
+            case "int":
+                return {
+                    tag: "const",
+                    val: { tag: "int", value: k.value },
+                };
+            case "bool":
+                return {
+                    tag: "const",
+                    val: { tag: "int", value: k.value ? 1 : 0 },
+                };
+            case "str":
+            case "group":
+            case "array":
+            case "repeat":
+            case "struct":
+            case "ref":
+            case "deref":
+            case "elem":
+            case "field":
+            case "index":
+            case "call":
+            case "unary":
+            case "binary":
+            case "block":
+            case "if":
+            case "loop":
+            case "while":
+            case "for":
+            case "c_for": {
+                const ty = this.ch.exprTy(expr);
+                const rval = this.lowerExpr(expr);
+                const local = this.local(ty);
+                this.addStmt({
+                    tag: "assign",
+                    place: { local, proj: [] },
+                    rval,
+                });
+                return { tag: "move", place: { local, proj: [] } };
+            }
+        }
+        exhausted(k);
+    }
+
+    private lowerPathExprToOperand(
+        expr: ast.Expr,
+        kind: ast.PathExpr,
+    ): Operand {
+        const re = this.re.exprRes(expr.id);
+        switch (re.kind.tag) {
+            case "error":
+                return { tag: "error" };
+            case "local": {
+                const patRes = this.re.patRes(re.kind.id);
+                const ty = this.ch.exprTy(expr);
+                let local: LocalId;
+                if (this.reLocals.has(re.kind.id)) {
+                    local = this.reLocals.get(re.kind.id)!;
+                } else {
+                    local = this.local(ty);
+                    this.reLocals.set(re.kind.id, local);
+                }
+                if (patRes.kind.tag === "fn_param") {
+                    this.paramLocals.set(local, patRes.kind.paramIdx);
+                }
+                const isCopyable = (() => {
+                    switch (ty.kind.tag) {
+                        case "error":
+                        case "unknown":
+                            return false;
+                        case "null":
+                        case "int":
+                        case "bool":
+                            return true;
+                        case "fn":
+                            return false;
+                    }
+                    exhausted(ty.kind);
+                })();
+                return {
+                    tag: isCopyable ? "copy" : "move",
+                    place: { local, proj: [] },
+                };
+            }
+            case "fn": {
+                const { item, kind } = re.kind;
+                return { tag: "const", val: { tag: "fn", item, kind } };
+            }
+        }
+        exhausted(re.kind);
+    }
+
+    private local(ty: Ty, ident?: ast.Ident): LocalId {
         const id = this.localIds.nextThenStep();
-        this.locals.set(id, { id, ty });
+        this.locals.set(id, { id, ty, ident });
         return id;
     }
 
-    private pushBlock(): BlockId {
+    private pushBlock(): Block {
         const id = this.blockIds.nextThenStep();
         const block: Block = {
             id,
@@ -336,15 +430,15 @@ export class FnLowerer {
         };
         this.blocks.set(id, block);
         this.currentBlock = block;
-        return id;
+        return block;
     }
 
-    private setTer(kind: TerKind) {
-        this.currentBlock!.terminator = { kind };
+    private setTer(kind: TerKind, block = this.currentBlock!) {
+        block.terminator = { kind };
     }
 
-    private addStmt(kind: StmtKind) {
-        this.currentBlock!.stmts.push({ kind });
+    private addStmt(kind: StmtKind, block = this.currentBlock!) {
+        block.stmts.push({ kind });
     }
 }
 
diff --git a/slige/compiler/middle/mir.ts b/slige/compiler/middle/mir.ts
index f655904..dceea9f 100644
--- a/slige/compiler/middle/mir.ts
+++ b/slige/compiler/middle/mir.ts
@@ -1,4 +1,5 @@
 import { IdBase, IdMap } from "@slige/common";
+import * as ast from "@slige/ast";
 import { Ty } from "@slige/ty";
 
 export type Fn = {
@@ -6,6 +7,9 @@ export type Fn = {
     locals: IdMap<LocalId, Local>;
     blocks: IdMap<BlockId, Block>;
     entry: BlockId;
+    paramLocals: IdMap<LocalId, number>;
+    astItem: ast.Item;
+    astItemKind: ast.FnItem;
 };
 
 export type LocalId = IdBase & { readonly _: unique symbol };
@@ -13,6 +17,7 @@ export type LocalId = IdBase & { readonly _: unique symbol };
 export type Local = {
     id: LocalId;
     ty: Ty;
+    ident?: ast.Ident;
 };
 
 export type BlockId = IdBase & { readonly _: unique symbol };
@@ -102,6 +107,7 @@ export type BinaryType =
 export type UnaryType = "not" | "neg";
 
 export type Operand =
+    | { tag: "error" }
     | { tag: "copy"; place: Place }
     | { tag: "move"; place: Place }
     | { tag: "const"; val: Const };
@@ -109,5 +115,5 @@ export type Operand =
 export type Const =
     | { tag: "null" }
     | { tag: "int"; value: number }
-    | { tag: "bool"; value: boolean }
-    | { tag: "string"; value: string };
+    | { tag: "str"; value: string }
+    | { tag: "fn"; item: ast.Item; kind: ast.FnItem };
diff --git a/slige/compiler/program.slg b/slige/compiler/program.slg
index a79216a..5d9dedc 100644
--- a/slige/compiler/program.slg
+++ b/slige/compiler/program.slg
@@ -5,7 +5,10 @@ fn add(lhs: int, rhs: int) -> int {
 
 fn main() {
     let a = 5;
-    let b = 7;
+    let b = 7 + a;
+
+    if true {}
+
     let c = add(a, b);
 }
 
diff --git a/slige/compiler/stringify/hir.ts b/slige/compiler/stringify/hir.ts
index 6e11a30..4fac324 100644
--- a/slige/compiler/stringify/hir.ts
+++ b/slige/compiler/stringify/hir.ts
@@ -112,7 +112,9 @@ export class HirStringifyer {
                     this.expr(k.right)
                 }`;
             case "block":
+                return todo(k.tag);
             case "if":
+                return `if ${this.expr(k.cond)}`;
             case "loop":
             case "while":
             case "for":
@@ -164,6 +166,8 @@ export class HirStringifyer {
                 return "null";
             case "int":
                 return "int";
+            case "bool":
+                return "bool";
             case "fn":
                 return `fn ${k.item.ident}(${
                     k.params.map((param) => this.ty(param)).join(", ")
diff --git a/slige/compiler/stringify/mir.ts b/slige/compiler/stringify/mir.ts
index 1490de6..d1d201b 100644
--- a/slige/compiler/stringify/mir.ts
+++ b/slige/compiler/stringify/mir.ts
@@ -26,11 +26,35 @@ export class MirFnStringifyer {
     ) {}
 
     public fn(fn: Fn): string {
-        return `fn ${fn.label} {\n${
-            fn.locals.values().toArray()
-                .map((local) => this.localDef(local))
-                .join("\n")
-        }\n${
+        for (
+            const [idx, id] of fn.blocks
+                .keys()
+                .toArray()
+                .entries()
+        ) {
+            this.blockIds.set(id, idx);
+        }
+        for (
+            const [idx, id] of fn.locals
+                .keys()
+                .toArray()
+                .entries()
+        ) {
+            this.localIds.set(id, idx);
+        }
+        const locals = fn.locals.values().toArray();
+        const paramsStr = locals
+            .filter((local) => fn.paramLocals.has(local.id))
+            .map((local) => [local, fn.paramLocals.get(local.id)!] as const)
+            .toSorted((a, b) => a[1] - b[1])
+            .map(([local]) => fn.locals.get(local.id)!)
+            .map((local) => this.localDef(local))
+            .join(", ");
+        const localsStr = locals
+            .filter((local) => !fn.paramLocals.has(local.id))
+            .map((local) => `#let ${this.localDef(local)}`)
+            .join("\n");
+        return `fn ${fn.label}(${paramsStr}) {\n${localsStr}\n${
             fn.blocks.values().toArray()
                 .map((block) => this.block(block))
                 .join("\n")
@@ -38,19 +62,20 @@ export class MirFnStringifyer {
     }
 
     private localDef(local: Local): string {
-        const id = this.localIds.size;
-        this.localIds.set(local.id, id);
-        return `#let %${id}: ${tyToString(this.ctx, local.ty)}`;
+        const ident = local.ident && ` // ${local.ident.text}` || "";
+        return `${this.local(local.id)}: ${this.ty(local.ty)}${ident}`;
     }
 
     private block(block: Block): string {
-        const id = this.blockIds.size;
-        this.blockIds.set(block.id, id);
+        const id = this.blockIds.get(block.id);
         return `#.b${id}: {\n${
-            block.stmts
-                .map((stmt) => this.stmt(stmt))
+            [
+                ...block.stmts
+                    .map((stmt) => this.stmt(stmt)),
+                this.ter(block.terminator),
+            ]
                 .join("\n")
-        }\n${this.ter(block.terminator)}\n#}`;
+        }\n#}`;
     }
 
     private stmt(stmt: Stmt): string {
@@ -76,8 +101,17 @@ export class MirFnStringifyer {
             case "unset":
                 return "##<unset>;";
             case "goto":
-            case "switch":
-                return todo(k.tag);
+                return `##goto ${this.blockId(k.target)}`;
+            case "switch": {
+                const discr = this.operand(k.discr);
+                const targets = k.targets
+                    .map((target) =>
+                        `\n###${target.value} => ${this.blockId(target.target)}`
+                    )
+                    .join("");
+                const otherwise = this.blockId(k.otherwise);
+                return `##switch ${discr}${targets}\n###_ => ${otherwise}`;
+            }
             case "return":
                 return `##return;`;
             case "unreachable":
@@ -122,14 +156,16 @@ export class MirFnStringifyer {
             case "ref":
             case "ptr":
                 return todo(rval.tag);
-            case "binary":
-                return `${this.operand(rval.left)} ${rval.binaryType} ${
-                    this.operand(rval.right)
-                }`;
+            case "binary": {
+                const op = rval.binaryType;
+                const left = this.operand(rval.left);
+                const right = this.operand(rval.right);
+                return `${op}(${left}, ${right})`;
+            }
             case "unary":
                 return todo(rval.tag);
             case "call":
-                return `${this.operand(rval.func)}(${
+                return `call ${this.operand(rval.func)}(${
                     rval.args.map((arg) => this.operand(arg)).join(", ")
                 })`;
         }
@@ -138,6 +174,8 @@ export class MirFnStringifyer {
 
     private operand(operand: Operand): string {
         switch (operand.tag) {
+            case "error":
+                return `<error>`;
             case "copy":
                 return `copy ${this.place(operand.place)}`;
             case "move":
@@ -154,15 +192,23 @@ export class MirFnStringifyer {
                 return `null`;
             case "int":
                 return `${val.value}`;
-            case "bool":
-                return `${val.value}`;
-            case "string":
+            case "str":
                 return `"${val.value}"`;
+            case "fn":
+                return `${val.item.ident.text}`;
         }
         exhausted(val);
     }
 
+    private blockId(id: BlockId): string {
+        return `.b${this.blockIds.get(id)!}`;
+    }
+
     private local(local: LocalId): string {
-        return `%${this.localIds.get(local)!}`;
+        return `_${this.localIds.get(local)!}`;
+    }
+
+    private ty(ty: Ty): string {
+        return tyToString(this.ctx, ty);
     }
 }
diff --git a/slige/compiler/ty/to_string.ts b/slige/compiler/ty/to_string.ts
index 941c8bd..b3bae27 100644
--- a/slige/compiler/ty/to_string.ts
+++ b/slige/compiler/ty/to_string.ts
@@ -12,6 +12,8 @@ export function tyToString(ctx: Ctx, ty: Ty): string {
             return `null`;
         case "int":
             return `int`;
+        case "bool":
+            return `bool`;
         case "fn": {
             const identText = ctx.identText(k.item.ident.id);
             const params = k.params
diff --git a/slige/compiler/ty/ty.ts b/slige/compiler/ty/ty.ts
index 10fce19..ef01dd4 100644
--- a/slige/compiler/ty/ty.ts
+++ b/slige/compiler/ty/ty.ts
@@ -11,6 +11,7 @@ export type TyKind =
     | { tag: "unknown" }
     | { tag: "null" }
     | { tag: "int" }
+    | { tag: "bool" }
     | {
         tag: "fn";
         item: ast.Item;