diff --git a/compiler/ast.ts b/compiler/ast.ts
index 8a342e7..975f762 100644
--- a/compiler/ast.ts
+++ b/compiler/ast.ts
@@ -1,5 +1,5 @@
 import { Pos } from "./token.ts";
-import { VType } from "./vtype.ts";
+import { GenericArgsMap, VType } from "./vtype.ts";
 
 export type Stmt = {
     kind: StmtKind;
@@ -48,7 +48,12 @@ export type ExprKind =
     | { type: "group"; expr: Expr }
     | { type: "field"; subject: Expr; ident: string }
     | { type: "index"; subject: Expr; value: Expr }
-    | { type: "call"; subject: Expr; args: Expr[] }
+    | {
+        type: "call";
+        subject: Expr;
+        args: Expr[];
+        genericArgs?: GenericArgsMap;
+    }
     | { type: "path"; subject: Expr; ident: string }
     | { type: "etype_args"; subject: Expr; etypeArgs: EType[] }
     | { type: "unary"; unaryType: UnaryType; subject: Expr }
diff --git a/compiler/checker.ts b/compiler/checker.ts
index 07fe346..1da414f 100644
--- a/compiler/checker.ts
+++ b/compiler/checker.ts
@@ -414,75 +414,286 @@ export class Checker {
         const subject = this.checkExpr(expr.kind.subject);
         if (subject.type === "error") return subject;
         if (subject.type === "fn") {
-            if (subject.genericParams !== undefined) {
-                throw new Error("😭😭😭");
-            }
-            const args = expr.kind.args.map((arg) => this.checkExpr(arg));
-            if (args.length !== subject.params.length) {
+            if (expr.kind.args.length !== subject.params.length) {
                 this.report(
                     `incorrect number of arguments` +
                         `, expected ${subject.params.length}`,
                     pos,
                 );
             }
-            for (let i = 0; i < args.length; ++i) {
-                if (!vtypesEqual(args[i], subject.params[i].vtype)) {
-                    this.report(
-                        `incorrect argument ${i} '${subject.params[i].ident}'` +
-                            `, expected ${
-                                vtypeToString(subject.params[i].vtype)
-                            }` +
-                            `, got ${vtypeToString(args[i])}`,
-                        pos,
-                    );
-                    break;
-                }
-            }
-            return subject.returnType;
-        }
-        if (subject.type === "generic_spec" && subject.subject.type === "fn") {
-            const inner = subject.subject;
-            const params = inner.params;
             const args = expr.kind.args.map((arg) => this.checkExpr(arg));
-            if (args.length !== params.length) {
-                this.report(
-                    `incorrect number of arguments` +
-                        `, expected ${params.length}`,
+            if (subject.genericParams === undefined) {
+                return this.checkCallExprNoGenericsTail(
+                    expr,
+                    subject,
+                    args,
                     pos,
                 );
             }
-            for (let i = 0; i < args.length; ++i) {
-                const vtypeCompatible = vtypesEqual(
-                    args[i],
-                    params[i].vtype,
-                    subject.genericArgs,
-                );
-                if (!vtypeCompatible) {
-                    this.report(
-                        `incorrect argument ${i} '${inner.params[i].ident}'` +
-                            `, expected ${
-                                vtypeToString(
-                                    extractGenericType(
-                                        params[i].vtype,
-                                        subject.genericArgs,
-                                    ),
-                                )
-                            }` +
-                            `, got ${vtypeToString(args[i])}`,
-                        pos,
-                    );
-                    break;
-                }
-            }
-            return extractGenericType(
-                subject.subject.returnType,
-                subject.genericArgs,
+            return this.checkCallExprInferredGenericsTail(
+                expr,
+                subject,
+                args,
+                pos,
             );
         }
+        if (subject.type === "generic_spec" && subject.subject.type === "fn") {
+            return this.checkCallExprExplicitGenericsTail(expr, subject);
+        }
         this.report("cannot call non-fn", pos);
         return { type: "error" };
     }
 
+    private checkCallExprNoGenericsTail(
+        expr: Expr,
+        subject: VType,
+        args: VType[],
+        pos: Pos,
+    ): VType {
+        if (
+            expr.kind.type !== "call" || subject.type !== "fn"
+        ) {
+            throw new Error();
+        }
+        for (let i = 0; i < args.length; ++i) {
+            if (this.vtypeContainsGeneric(args[i])) {
+                this.report(
+                    `amfibious generic parameter for argument ${i}, please specify generic types explicitly`,
+                    pos,
+                );
+                return { type: "error" };
+            }
+        }
+
+        for (let i = 0; i < args.length; ++i) {
+            if (!vtypesEqual(args[i], subject.params[i].vtype)) {
+                this.report(
+                    `incorrect argument ${i} '${subject.params[i].ident}'` +
+                        `, expected ${vtypeToString(subject.params[i].vtype)}` +
+                        `, got ${vtypeToString(args[i])}`,
+                    pos,
+                );
+                break;
+            }
+        }
+
+        return subject.returnType;
+    }
+
+    private checkCallExprInferredGenericsTail(
+        expr: Expr,
+        subject: VType,
+        args: VType[],
+        pos: Pos,
+    ): VType {
+        if (
+            expr.kind.type !== "call" || subject.type !== "fn" ||
+            subject.genericParams === undefined
+        ) {
+            throw new Error();
+        }
+        const genericArgsRes = this.inferGenericArgs(
+            subject.genericParams,
+            subject.params,
+            args,
+            pos,
+        );
+        if (!genericArgsRes.ok) {
+            return { type: "error" };
+        }
+        const genericArgs = genericArgsRes.value;
+
+        for (let i = 0; i < args.length; ++i) {
+            const vtypeCompatible = vtypesEqual(
+                args[i],
+                subject.params[i].vtype,
+                genericArgs,
+            );
+            if (!vtypeCompatible) {
+                this.report(
+                    `incorrect argument ${i} '${subject.params[i].ident}'` +
+                        `, expected ${
+                            vtypeToString(
+                                extractGenericType(
+                                    subject.params[i].vtype,
+                                    genericArgs,
+                                ),
+                            )
+                        }` +
+                        `, got ${vtypeToString(args[i])}`,
+                    pos,
+                );
+                break;
+            }
+        }
+
+        expr.kind.genericArgs = genericArgs;
+        return this.concretizeVType(subject.returnType, genericArgs);
+    }
+
+    private inferGenericArgs(
+        genericParams: VTypeGenericParam[],
+        params: VTypeParam[],
+        args: VType[],
+        pos: Pos,
+    ): { ok: true; value: GenericArgsMap } | { ok: false } {
+        const genericArgs: GenericArgsMap = {};
+
+        for (let i = 0; i < params.length; ++i) {
+            if (!this.vtypeContainsGeneric(params[i].vtype)) {
+                continue;
+            }
+            const {
+                a: generic,
+                b: concrete,
+            } = this.reduceToSignificant(params[i].vtype, args[i]);
+            if (generic.type !== "generic") {
+                throw new Error();
+            }
+            const paramId = generic.param.id;
+            if (
+                paramId in genericArgs &&
+                !vtypesEqual(genericArgs[paramId], concrete)
+            ) {
+                this.report(
+                    `according to inferrence, argument ${i} has a conflicting type`,
+                    pos,
+                );
+                return { ok: false };
+            }
+            genericArgs[paramId] = concrete;
+        }
+
+        for (const param of genericParams) {
+            if (!(param.id in genericArgs)) {
+                this.report(`could not infer generic type ${param.ident}`, pos);
+                return { ok: false };
+            }
+        }
+
+        return { ok: true, value: genericArgs };
+    }
+
+    private reduceToSignificant(a: VType, b: VType): { a: VType; b: VType } {
+        if (a.type !== b.type) {
+            return { a, b };
+        }
+        if (a.type === "array" && b.type === "array") {
+            return this.reduceToSignificant(a.inner, b.inner);
+        }
+        throw new Error("idk what to do here");
+    }
+
+    private vtypeContainsGeneric(vtype: VType): boolean {
+        switch (vtype.type) {
+            case "error":
+            case "string":
+            case "unknown":
+            case "null":
+            case "int":
+            case "bool":
+                return false;
+            case "array":
+                return this.vtypeContainsGeneric(vtype.inner);
+            case "struct":
+                return vtype.fields.some((field) =>
+                    this.vtypeContainsGeneric(field.vtype)
+                );
+            case "fn":
+                throw new Error("not implemented");
+            case "generic":
+                return true;
+            case "generic_spec":
+                throw new Error("listen kid, grrrrrrrr");
+        }
+    }
+
+    private checkCallExprExplicitGenericsTail(
+        expr: Expr,
+        subject: VType,
+    ): VType {
+        if (
+            expr.kind.type !== "call" || subject.type !== "generic_spec" ||
+            subject.subject.type !== "fn"
+        ) {
+            throw new Error();
+        }
+        const pos = expr.pos;
+        const inner = subject.subject;
+        const params = inner.params;
+        const args = expr.kind.args.map((arg) => this.checkExpr(arg));
+        if (args.length !== params.length) {
+            this.report(
+                `incorrect number of arguments` +
+                    `, expected ${params.length}`,
+                pos,
+            );
+        }
+        for (let i = 0; i < args.length; ++i) {
+            const vtypeCompatible = vtypesEqual(
+                args[i],
+                params[i].vtype,
+                subject.genericArgs,
+            );
+            if (!vtypeCompatible) {
+                this.report(
+                    `incorrect argument ${i} '${inner.params[i].ident}'` +
+                        `, expected ${
+                            vtypeToString(
+                                extractGenericType(
+                                    params[i].vtype,
+                                    subject.genericArgs,
+                                ),
+                            )
+                        }` +
+                        `, got ${vtypeToString(args[i])}`,
+                    pos,
+                );
+                break;
+            }
+        }
+
+        expr.kind.genericArgs = subject.genericArgs;
+        return this.concretizeVType(
+            subject.subject.returnType,
+            subject.genericArgs,
+        );
+    }
+
+    private concretizeVType(
+        vtype: VType,
+        generics: GenericArgsMap,
+    ): VType {
+        switch (vtype.type) {
+            case "error":
+            case "unknown":
+            case "string":
+            case "null":
+            case "int":
+            case "bool":
+                return vtype;
+            case "array":
+                return {
+                    type: "array",
+                    inner: this.concretizeVType(vtype.inner, generics),
+                };
+            case "struct":
+                return {
+                    type: "struct",
+                    fields: vtype.fields.map((field) => ({
+                        ...field,
+                        vtype: this.concretizeVType(field.vtype, generics),
+                    })),
+                };
+            case "fn":
+                throw new Error("not implemented");
+            case "generic":
+                return generics[vtype.param.id];
+            case "generic_spec":
+                throw new Error("not implemented");
+        }
+    }
+
     public checkPathExpr(expr: Expr): VType {
         if (expr.kind.type !== "path") {
             throw new Error();
diff --git a/compiler/compiler.ts b/compiler/compiler.ts
index 026a173..aafc601 100644
--- a/compiler/compiler.ts
+++ b/compiler/compiler.ts
@@ -50,7 +50,7 @@ export class Compiler {
 
         const lowerer = new Lowerer(monoFns, callMap, lexer.currentPos());
         const { program, fnNames } = lowerer.lower();
-        //lowerer.printProgram();
+        lowerer.printProgram();
 
         return { program, fnNames };
     }
diff --git a/compiler/mono.ts b/compiler/mono.ts
index fa6d00a..9ccc45b 100644
--- a/compiler/mono.ts
+++ b/compiler/mono.ts
@@ -3,6 +3,7 @@ import { AstVisitor, visitExpr, VisitRes, visitStmts } from "./ast_visitor.ts";
 import { GenericArgsMap, VType } from "./vtype.ts";
 
 export class Monomorphizer {
+    private fnIdCounter = 0;
     private fns: MonoFnsMap = {};
     private callMap: MonoCallNameGenMap = {};
     private allFns: Map<number, Stmt>;
@@ -22,11 +23,13 @@ export class Monomorphizer {
         stmt: Stmt,
         genericArgs?: GenericArgsMap,
     ): MonoFn {
-        const nameGen = monoFnNameGen(stmt, genericArgs);
+        const id = this.fnIdCounter;
+        this.fnIdCounter += 1;
+        const nameGen = monoFnNameGen(id, stmt, genericArgs);
         if (nameGen in this.fns) {
             return this.fns[nameGen];
         }
-        const monoFn = { nameGen, stmt, genericArgs };
+        const monoFn = { id, nameGen, stmt, genericArgs };
         this.fns[nameGen] = monoFn;
         const calls = new CallCollector().collect(stmt);
         for (const call of calls) {
@@ -34,7 +37,10 @@ export class Monomorphizer {
             if (call.kind.type !== "call") {
                 throw new Error();
             }
-            if (call.kind.subject.vtype?.type === "fn") {
+            if (
+                call.kind.subject.vtype?.type === "fn" &&
+                call.kind.subject.vtype.genericParams === undefined
+            ) {
                 const fn = this.allFns.get(call.kind.subject.vtype.stmtId);
                 if (fn === undefined) {
                     throw new Error();
@@ -43,6 +49,40 @@ export class Monomorphizer {
                 this.callMap[call.id] = monoFn.nameGen;
                 continue;
             }
+            if (
+                call.kind.subject.vtype?.type === "fn" &&
+                call.kind.subject.vtype.genericParams !== undefined
+            ) {
+                if (call.kind.genericArgs === undefined) {
+                    throw new Error();
+                }
+                const genericArgs = call.kind.genericArgs;
+
+                const monoArgs: GenericArgsMap = {};
+                for (const key in call.kind.genericArgs) {
+                    const vtype = genericArgs[key];
+                    if (vtype.type === "generic") {
+                        if (genericArgs === undefined) {
+                            throw new Error();
+                        }
+                        monoArgs[key] = genericArgs[vtype.param.id];
+                    } else {
+                        monoArgs[key] = vtype;
+                    }
+                }
+
+                const fnType = call.kind.subject.vtype!;
+                if (fnType.type !== "fn") {
+                    throw new Error();
+                }
+                const fn = this.allFns.get(fnType.stmtId);
+                if (fn === undefined) {
+                    throw new Error();
+                }
+                const monoFn = this.monomorphizeFn(fn, monoArgs);
+                this.callMap[call.id] = monoFn.nameGen;
+                continue;
+            }
             if (call.kind.subject.vtype?.type === "generic_spec") {
                 const genericSpecType = call.kind.subject.vtype!;
                 if (genericSpecType.subject.type !== "fn") {
@@ -85,6 +125,7 @@ export type MonoResult = {
 export type MonoFnsMap = { [nameGen: string]: MonoFn };
 
 export type MonoFn = {
+    id: number;
     nameGen: string;
     stmt: Stmt;
     genericArgs?: GenericArgsMap;
@@ -92,7 +133,11 @@ export type MonoFn = {
 
 export type MonoCallNameGenMap = { [exprId: number]: string };
 
-function monoFnNameGen(stmt: Stmt, genericArgs?: GenericArgsMap): string {
+function monoFnNameGen(
+    id: number,
+    stmt: Stmt,
+    genericArgs?: GenericArgsMap,
+): string {
     if (stmt.kind.type !== "fn") {
         throw new Error();
     }
@@ -100,12 +145,12 @@ function monoFnNameGen(stmt: Stmt, genericArgs?: GenericArgsMap): string {
         return "main";
     }
     if (genericArgs === undefined) {
-        return `${stmt.kind.ident}_${stmt.id}`;
+        return `${stmt.kind.ident}_${id}`;
     }
     const args = Object.values(genericArgs)
         .map((arg) => vtypeNameGenPart(arg))
         .join("_");
-    return `${stmt.kind.ident}_${stmt.id}_${args}`;
+    return `${stmt.kind.ident}_${id}_${args}`;
 }
 
 function vtypeNameGenPart(vtype: VType): string {
diff --git a/examples/generic_array.slg b/examples/generic_array.slg
index 11cb0bf..82cf74e 100644
--- a/examples/generic_array.slg
+++ b/examples/generic_array.slg
@@ -1,4 +1,4 @@
-
+//
 
 fn array_new<T>() -> [T] #[builtin(ArrayNew)] {}
 fn array_push<T>(array: [T], value: T) #[builtin(ArrayPush)] {}
@@ -8,12 +8,12 @@ fn array_at<T>(array: [T], index: int) -> string #[builtin(ArrayAt)] {}
 
 fn main() {
     let strings = array_new::<string>();
-    array_push::<string>(strings, "hello");
-    array_push::<string>(strings, "world");
+    array_push(strings, "hello");
+    array_push(strings, "world");
 
     let ints = array_new::<int>();
-    array_push::<int>(ints, 1);
-    array_push::<int>(ints, 2);
+    array_push(ints, 1);
+    array_push(ints, 2);
 }
 
 
diff --git a/slige-run.sh b/slige-run.sh
index 610eabd..056163a 100755
--- a/slige-run.sh
+++ b/slige-run.sh
@@ -13,7 +13,7 @@ fi
 
 echo Compiling $1...
 
-deno run --allow-read --allow-write compiler/main.ts $1
+deno run --allow-read --allow-write --check compiler/main.ts $1
 
 echo Running out.slgbc...