feat: add TryFrom

README.md

@@ -7,7 +7,7 @@ Nodash is a utility library for [Noir](https://github.com/noir-lang/noir) langua
 Put this into your Nargo.toml.
 
 ```toml
-nodash = { git = "https://github.com/olehmisar/nodash/", tag = "v0.40.0" }
+nodash = { git = "https://github.com/olehmisar/nodash/", tag = "v0.40.1" }
 ```
 
 ## Docs
@@ -129,6 +129,19 @@ use nodash::str_to_u64;
 assert(str_to_u64("02345678912345678912") == 02345678912345678912);
 ```
 
+### `try_from`
+
+Fail-able conversion.
+
+````rs
+use nodash::TryFrom;
+
+assert(u8::try_from(123) == 123);
+u8::try_from(256); // runtime error
+
+assert(u128::try_from(123) == 123);
+```
+
 ### `ord`
 
 Returns the ASCII code of a single character.
@@ -137,7 +150,7 @@ Returns the ASCII code of a single character.
 use nodash::ord;
 
 assert(ord("a") == 97);
-```
+````
 
 ### `ArrayExtensions`
 

src/convert.nr

@@ -0,0 +1,82 @@
+pub trait TryFrom<T> {
+    /// Convert or fail.
+    fn try_from(input: T) -> Self;
+}
+
+impl TryFrom<Field> for u8 {
+    fn try_from(input: Field) -> Self {
+        input.assert_max_bit_size::<8>();
+        input as u8
+    }
+}
+
+impl TryFrom<Field> for u16 {
+    fn try_from(input: Field) -> Self {
+        input.assert_max_bit_size::<16>();
+        input as u16
+    }
+}
+
+impl TryFrom<Field> for u32 {
+    fn try_from(input: Field) -> Self {
+        input.assert_max_bit_size::<32>();
+        input as u32
+    }
+}
+
+impl TryFrom<Field> for u64 {
+    fn try_from(input: Field) -> Self {
+        input.assert_max_bit_size::<64>();
+        input as u64
+    }
+}
+
+impl TryFrom<Field> for u128 {
+    fn try_from(input: Field) -> Self {
+        input.assert_max_bit_size::<128>();
+        input as u128
+    }
+}
+
+impl TryFrom<Field> for i8 {
+    fn try_from(input: Field) -> Self {
+        input.assert_max_bit_size::<8>();
+        input as i8
+    }
+}
+
+impl TryFrom<Field> for i16 {
+    fn try_from(input: Field) -> Self {
+        input.assert_max_bit_size::<16>();
+        input as i16
+    }
+}
+
+impl TryFrom<Field> for i32 {
+    fn try_from(input: Field) -> Self {
+        input.assert_max_bit_size::<32>();
+        input as i32
+    }
+}
+
+impl TryFrom<Field> for i64 {
+    fn try_from(input: Field) -> Self {
+        input.assert_max_bit_size::<64>();
+        input as i64
+    }
+}
+
+mod tests {
+    use super::TryFrom;
+
+    #[test]
+    fn test_try_from() {
+        assert(u8::try_from(123) == 123);
+        assert(u128::try_from(123) == 123);
+    }
+
+    #[test(should_fail_with = "call to assert_max_bit_size")]
+    fn test_try_from_fail() {
+        let _ = u8::try_from(256);
+    }
+}

src/lib.nr

@@ -1,3 +1,4 @@
+mod convert;
 mod hash;
 mod math;
 mod solidity;
@@ -7,6 +8,7 @@ mod array;
 mod validate_inputs;
 
 pub use array::pack_bytes;
+pub use convert::TryFrom;
 pub use hash::{keccak256, pedersen, poseidon2, sha256};
 pub use math::{clamp, div_ceil, sqrt::sqrt};
 pub use string::{field_to_hex, ord, str_to_u64, to_hex_string_bytes};